Teachers of composition urge their students to (i)__avoid confusion____ in their writing and instead use clear, simple language. Why use a (ii)_difficult to understand _ vocabulary when (iii)__clear__ phrasing conveys one’s meaning so much more effectively?
so first blank clue comes from ''instead use clear, simple language'' in the blank work must be avoid confusion and so B fits perfectly, from this context we can understand author is trying avoid difficult vocabulary and encourage use of simple vocabulary. so we difficult to understand closely indicate F is the answer we are looking for, and 3rd blank is clear indicates a limpid is the final answer.