Answer:
C). Antarctica's icebergs would bring
Explanation:
As per the question, the next words to complete the sentence would be 'Antarctica's icebergs would bring' as it is grammatically and lexically coherent. It offers the subject correctly after the subordinate clause which is modifying it and doesn't include any kinds of errors associated with the pronoun or modification. While the other options(choices A and D) fail to clearly refer to 'they' and option B is incorrect due to the illogical implementation of 'many arid areas.' Thus, option C is the correct answer and the complete sentence reads as:
"If they could be floated north before melting, Antarctica's icebergs would bring many arid areas relief from drought."