Question

a(n) dropdown clause should always be separated from the rest of the sentence by commas.

Explanation:

Identify the grammatical rule for comma separation

The question asks which type of clause must always be separated from the rest of the sentence by commas.

Analyze clause types and punctuation

Using our understanding of Independent Clauses and Dependent Clauses, we can evaluate how different clauses are punctuated:

• An essential (restrictive) clause limits the meaning of the noun it modifies and is never set off by commas.
• A nonessential (nonrestrictive) clause adds extra, non-essential information about a noun. Because this information is parenthetical, a nonrestrictive clause should always be separated from the rest of the sentence by commas.

Answer:

A(n) <blank>nonrestrictive</blank> clause should always be separated from the rest of the sentence by commas.