Identify the best way to improve the bold part of the given sentence. If there is no improvement required, select ‘no improvement’. Mental intelligence and common sense are essential for outstanding achievement because they involve your natural ability to comprehend difficult concepts quicker and to analyse them clearly and incisively. Correct Answer one's natural ability to comprehend difficult concepts quickly and to analyse them clearly and incisively. The correct answer is option 3 i.e. one's natural ability to comprehend difficult concepts quickly and to analyse them clearly and incisively. We have to follow the rule of parallelism here for making the sentence grammatically correct. adverb + and + adverb ( clearly and incisively) To + v1 ( to comprehend) Both the rules should be followed for the statement to be correct. These rules have been followed by option 3 so, this is right to choose as the correct answer. The correct sentence will be- Mental intelligence and common sense are essential for outstanding achievement because they involve one's natural ability to comprehend difficult concepts quickly and to analyse them clearly and incisively.