Explanation:

Correct Answer is (c).The original sentence is erroneous.
Reason: The word ‘communication’ means ‘the imparting or exchanging of information by speaking, writing, or using some other medium’ whereas the word ‘communications’. When used in the plural form, the word ‘communications’ also refers to ‘the technology employed in transmitting messages’. Here the latter is being referred to. Hence ‘communications’ should be used in place of ‘communication’ to make the sentence grammatically correct.
Among the given choices, only option C replaces the given bold part most appropriately.
The sentence after replacement becomes:
On 5G, Modi told Trump that it was a new area in communications that provided an opportunity for collaboration between India and the US.Option C is hence the correct answer.