Select the most appropriate option to fill in blank no. 3.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. enhance.
"Enhance" means to improve, increase, or strengthen something. In this context, it means improving one's ability to concentrate.
The sentence discusses difficulty in maintaining focus and then introduces techniques to help with it. The natural verb to fit here is "enhance," as it conveys the idea of making concentration better.