40.
Your Answer is
Correct Answer is H
Explanation
Item F: Both before and after the semicolon are complete sentences, and item F is wrong.
G item: In that sea lived a great variety of marine animals is an inverted sentence, because there is no conjunction, so no verbs can appear in the underlined part, and item G is wrong.
Item J: The mistake is that the two nouns crinoids and animals cannot be juxtaposed. The colon indicates the explanation, and the content after the colon is the explanation of the crinoids.