Answer: especially surrogacy has dramatically increased in recent years.

Explanation:
Specially vs especially (Specially means exclusively for, especially means-for a particular purpose); 'especially' suit the context better because 'infertility treatments' are mentioned as the class of treatments the tourists go for. Options 3 and 4 are eliminated. 'The number of foreigners' is the subject of the sentence. “the number" is always singular, hence 'has' is the correct verb. 

Answer: whose many ”gee-whiz” feature have been widely reported.

Explanation:
Who's vs whose-whose is the possessive of who. 'many features' is plural, hence the verb has to be the plural 'have'.

Answer: compared the choice of Liu for the Nobel Prize to that of Obama,

Explanation:
Choice is compared, hence that of (choice of) is essential. Otherwise choice and Obama are directly compared making it an error. To identify either the similarities or the differences between two things, use "compare to." To identify both the similarities and the differences (at the same time), use "compare with." (Compared with' places the things compared on equal level.) India is often compared with China. India is often compared to the US. In comparing with something, one finds or discusses both things that are alike and things that are different.

Answer: its mostly rich members to slow from 2.8% in 2010 to 2.3% in 2011,

Explanation:
The OECD is singular (that is why the verb is 'expects' rather than expect; the pronoun has to be consistent, hence its is necessary- their is incorrect. 'mostly rich members' is correct, 'their most rich members’ is vague. 'from' needs to be followed by 'to', not 'and.' Option 4 corrects these errors.

Answer: which means all map projections distort in one way or another.

Explanation:
The shift to future tense is unnecessary from the present 'cannot be represented' as it is a fact. It is an error to change which to that, as which introduces a descriptive clause. 'one way or another' is the correct idiom.

Answer: has been pinned on many things, including a more calorific diet,

Explanation:
Since the subject is 'the blame'-the verb has to be singular "has'. 'pinned on' is correct idiom. 'A more calorific diet' is parallel with 'the spread of ..' and a lack of Hence option 4 is faulty parallelism.

Answer: is believed by many nutritionists to be a factor in putting on weight.

Explanation:
There are there are two clauses in this sentence: The tendency to ent lute is believed (by nutritionists) to be a factor in putting on weight and (though) it has never been tested properly. The first clause can also be correctly constructed as "The tendency to eat lute, many nutritionists believe, is a factor in putting on weight." But, this is not among the options. "believed .... as a factor” is incorrect.

Answer: some 63% still use the old XP version launched in 2001; in America, the proportion of XP users is

Explanation:
Portions (per cent, fractions etc..) the verb will agree with the noun what follows the of (50 of the people come from ....,. 50% of the money comes from etc) In this sentence the n noun is machines; hence, the verb 'use' is correct. When there is already a comma in any of the punctuation that replaces a conjunction has to be a semicolon. In the above sentence, there is no conjunction. Option 3 makes the sentence incorrect because the sentence is not saying "launched in 2001 in America." "The proportion../'is the subject in the next clause; hence, the verb has to be singular ‘is'.

Answer: possess a unity which is quite as complete as that of our Western art.

Explanation:
There is no error in the original sentence nor does it need any improvement. 'features' needs a plural verb ’possess'. To establish comparison 'that of' is necessary.

Answer: Knowing by parts is science,

Explanation:
Faulty parallelism in all the other options.