A verb agreement question tests whether a verb matches its true subject when extra words separate them. First, sort the verb forms by number rather than tense: singular forms work with it, and plural forms work with they. Then ask who or what does what the verb says, and cross out extra words between commas. One thing takes a singular verb, while more than one takes a plural verb. The nearest noun may be inside the extra words rather than the subject.
Hints
- Hint 1
Look at the long phrase between the commas in the second sentence. Set it aside and ask what does the guiding.
- Hint 2
Check how the phrase between commas begins. Does it join another noun to the subject, or add information about the subject already named?
- Hint 3
Replace the remaining subject with it or they. Use that pronoun to test the verb forms.
Step-by-step
Sort by number, then find the subject
Step 1Sort the verb forms
The blank sits before geologists’ use of texture-based designations and supplies the second sentence’s verb. Since the choices are forms of the same verb, start with number rather than tense. Which forms work with they? Guide, are guiding, and have guided do, so they're plural forms; are and have are the helpers that show the number. We need the true subject to tell whether those forms can work.
- Step 2
Remove the added information
What does the guiding in this sentence? The commas set off together with other structural features produced by pressure rather than by a rock’s constituent minerals, so cross out that whole phrase and read the words left before the blank: The resulting texture. Texture is the true subject, and the comma phrase adds other features that matter along with it. A phrase beginning with together with doesn't join those features to the subject the way and would, so the subject is still singular. The details about pressure and minerals describe those other features inside the phrase; they don't change how many textures the subject names.
- Step 3
Match the verb to one texture
Shrink The resulting texture to it so we can test the verb without the long description. A singular subject takes a singular verb, and it guides works with one texture. The ending -s in guides marks the singular present-tense form, so it gives this sentence the agreement it needs. Choice A.