The suitable coordinating conjunction to fill in the blank is "and".
Explanation:
- Coordinating conjunctions are used to connect two independent clauses or sentences.
- In this sentence, the two independent clauses are "After a long day at work" and "Sunita comes home and relaxes for a while."
- The conjunction "and" is used to join these two clauses, indicating that both actions occur sequentially.
- The conjunction "but" would imply a contrast or contradiction between the two actions, which is not the intended meaning.
- The conjunction "although" would also imply a contrast or contradiction, which is not appropriate in this context.
- The conjunction "or" would provide an alternative action, which does not fit the logical sequence of the sentence.
Therefore, the correct answer is option B:
and.