Neither and either always take singular verbs when acting as the subject of a sentence.

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Here we have an example of a sentence in which the word "neither," not the plural noun "rosebushes," is the subject of the sentence. As per the stated rules above, "Neither" takes a singular verb when it acts as the subject of the sentence. Therefore, the singular verb "is" is correct. The sentence requires no alterations.

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Here we have a similar construction: in this sentence, the word "either" acts as the subject, and therefore requires a singular noun. If you're at all confused, a helpful tip is to think of the word "either" as an abbreviation of the phrase "either one". Once you do so, it's easier to see that the phrase "of us" is just filler (that you can cross it out). The subject of the sentence is "either (one)", and so this sentence therefore requires a singular verb: "is".

D. Plural / Singular

F. Or / Nor