The new University of Michigan study recommends that the state adopt

So here's my reasoning for A, please correct me if I'm wrong?

Adopts vs adopt (singular vs plural) - reforms are plural, hence adopt, hence A

The new University of Michigan study recommends that the state adopt several common-sense reforms, most of which have already shown promise in other parts of the country.

in the underlined part, there are 2 types of splits in answer choices
1. We might be tempted to think adopt is incorrect verb (must be singular, as state is singular)
2. have shown promise vs had shown promise

for 1, choose Plural, as it is a subjunctive verb, Study + recommends + that + the state + subjunctive verb: adopt. this eliminates B,C,D,E so A is correct.


for added confidence, usage of have shown is correct grammatically, as there is only one action, that too we are talking about effects of reforms that were adopted in past and their impact is still visible in the present. So use Have Shown.

VERITAS PREP OFFICIAL SOLUTION:

The most prominent decision point in this problem is the choice between “adopts,” “adopt” and “adopting”. While this type of verb choice is usually easy to assess, it is more difficult in this example. When certain verbs are used to express demands or suggestions such as insist, require, recommend, suggest, etc. the verb that follows requires a special conjugation in what is called the subjunctive mood (versus the normal indicative mood). Since these verbs are quite common in language, they are tested regularly on the GMAT and you must be on the lookout for this scenario. The rule is quite simple to learn: if you have a subjunctive verb followed by “that” then leave the verb that follows in the base form (the infinitive form without the “to”). So in this example you have the subjunctive verb “recommend” followed by “that” so the correct form of the verb is the base form “adopt” NOT the normal “adopts” that you would use in the indicative mood. As a result, you can eliminate (C), (D), and (E) immediately as “adopts” is wrong.

While there are other structures that can properly follow a subjunctive verb other than “that + base form of verb”, the structure in (B) is clearly incorrect: you cannot say, “the study recommends the state adopting…” so this too can be eliminated. Only (A) uses the correct “recommend that the state adopt…” and is thus the correct answer.