Directions: In this question, a sentence has been given with some of its part in bold. To make the sentence grammatically and idiomatically correct you have to replace the bold part with the correct alternative given below. If the sentence is correct as it is, mark 'No improvement required' as your answer.
» Explain it
E
The sentence is absolutely correct and thus needs no improvement.

Option E is hence the correct answer.
 
» Explain it
C
Option A and B are erroneous because ‘can return’ and ‘returned’ are verb phrases which aren’t parallel with the gerund phrase ‘becoming bizarre’. Options A and B hence get eliminated.

Option D, though, takes care of the parallel structure yet deviates the meaning of the sentence. 

Option C is the perfect choice among the given ones and must replace the bold part to make it a grammatically correct sentence.

Option C is hence the correct answer.
» Explain it
A
Option B is incorrect because the preposition ‘in’ is missing before “which”. This changes the meaning of the sentence. It indicates the UN touches the ways. Option B hence gets eliminated.

Option C is erroneous as well because “all” is not required. Plus, ‘everywhere’ is more appropriate than ‘every place’.

Option D is also incorrect because United Nations is a world famous organization and assumes the definite article ‘the’ before it.

Clearly, option A is most suitable choice among the given ones. 
» Explain it
A
Option D can be immediately eliminated because the phrasal verb ‘deal in’ which refers to ‘buying and selling something’ is not appropriate in the context.

Option B is verbose as “first starting with the one” is a repetition which can be avoided with ‘starting with the first’.

In option C, usage of passive voice (which is dealt with) doesn’t make any sense and is hence erroneous. This eliminates option C as well.

Clearly option A must be the correct answer.
» Explain it
E
The sentence is absolutely correct and thus needs no improvement.

Option E is hence the correct answer.