Constitutions may authorize judicial review, but their wording alone does not show how aggressively courts will use that power. The extent to which decisions issued by state supreme courts, rather than the stated preference of any one justice, ______ the range of laws left in force is therefore difficult for political scientists to infer from constitutional text alone.
Which choice completes the text so that it conforms to the conventions of Standard English?
For subject-verb agreement questions with long or embedded clauses, locate the clause containing the blank and identify the noun actually performing the verb’s action. Ignore interrupting phrases and nearby nouns, then match the verb to the subject in number.
Hints
Separate the clauses
The sentence contains one verb for “extent” and another verb in the clause beginning with “to which.” Focus on the clause containing the blank.
Remove the interruption
Temporarily set aside the phrase between the commas. Then identify which noun performs the action described by the missing verb.
Check agreement
Determine whether that subject is singular or plural, and select the verb form with the same number.
Step-by-step Explanation
Locate the relevant clause
The blank appears in the clause “decisions issued by state supreme courts ... ______ the range of laws.” The main clause has a separate subject-verb pair: “The extent ... is.”
Identify the verb's subject
The noun performing the action in the clause containing the blank is “decisions.” The phrase beginning with “rather than” does not change that subject.
Apply subject-verb agreement
Because “decisions” is plural, it requires the plural present-tense verb “constrain.”