The author never mentions whether the line of poetry could accurately describe Darwin’s theory. The argument is just concerned with demonstrating that Tennyson did not intend to refer to Darwin’s theory.

This statement isn’t supported by the argument. (B) is part of an assertion that Tennyson was referring to a theory other than Darwin’s, thus supporting the main conclusion that Tennyson wasn’t referring to Darwin’s theory.

This statement isn’t supported by the argument. (C) is used to support the main conclusion that Tennyson’s poem wasn’t referring to Darwin’s theory, because Tennyson wouldn’t have known about it.

This would be correct in a MSS or MBT question, but it isn’t the conclusion. The author is addressing the absence of a relationship between a line of poetry and Darwin’s theory, not the status of Darwin’s theory during a certain period.

This is a good restatement of the main conclusion. When the author claims that the evolutionists are mistaken about Tennyson’s poem referring to Darwin’s theory, that’s just another way to say that the poem did not refer to Darwin’s theory.