TOEIC® question, error recognition: set instead of sets

[Odysseus]

It is essential that she sets specific goals, or else productive time will be wasted.

A B C D

Please explain me why the answer is : B) set instead of sets
thank you!

[Torsten]

Hi, this is called 'subjunctive mood' where certain expressions and verbs are followed by an infinitive:
It's vital that he do as we say.
It's very important that she follow the procedure.
It's crucial she learn the correct use of the subjunctive mood.
I demand she adhere to our rules set forward in the guideline.

Let me know if this helps and welcome to english-test.net!
Regards,
Torsten

TOEIC listening, question-response: I bet the shipment will be late again.

[Odysseus]

Thank you for your information that really helped me.