ANSWER is 'No correction REQUIRED'. The underlined part does not need any improvement. We know that in the given sentence 'for' is a PREPOSITION. After preposition 'ing' form of the verb is used. Example: I will call you after arriving at the office.In the above example 'after' is a preposition after that 'ing' form is used. Therefore, the correct answer is Option 4. Correct Answer: No improvement required.