Select the most appropriate option that can substitute the underlined segment in the given sentence.
Shakespeare is great than any other English poet.

The correct option to substitute the underlined segment is was greater than.

Grammatical Breakdown:
1. Comparative Degree: In English grammar, when comparing a noun (Shakespeare) to a set of other nouns ("any other English poet"), we must use the comparative degree of the adjective. The comparative form of the positive adjective "great" is greater.
2. Conjunction Usage: The comparative degree is followed by the conjunction than to establish the comparison.
3. Sentence Structure: The original segment uses the positive adjective "great" incorrectly before "than". Replacing "great than" with "was greater than" provides the correct tense and comparative form, making the sentence grammatically sound.

Therefore, the segment "great than" should be replaced with was greater than.