4. a writer should (points: 5)
use sentences of equal length
use various sentence lengths and patterns
use words with complex derivations
use sentences with comma splices

A writer should use various sentence length and patterns. The correct option is B. If a writer use the same length of sentence with the same structure patterns, it will make the book look monotonous and boring to its readers. A writer up to splice up his book with varied sentence lengths and varied grammatical structure patterns.

Ialso agree with your statement

Syllable added to a root word to change its meaning : affixan independent word--example run,walk,book : free morphemeaffix that gives grammatical meaning such as tense or number : inflectiona word part that must attach to a word in order to be usable : bound morphemedegree of comparison formed by adding -er or more to an adjective : comparativedegree of comparison formed by adding -est or most to an adjective : superlativeaffix added to the beginning of a word : prefixaffix added to the end of a word : suffixroot word of lovable : lovetwo roots used together to form one word : combining form