13.

Answer and Explanation

Your Answer is

Correct Answer is B

Explanation

Item B: steady "stable" and rhythmic "rhythmic" are adjectives of the same level, and a comma is added in between, so B is correct.

A/C items: Adjectives modify nouns, multiple adjectives modify nouns, the last adjective and nouns are not separated by commas, so A/C is excluded.

Item D: There must be sentences before and after the semicolon, so D is excluded.