Which sentences contain a standard non-defining quantifier relative? Select all that apply.
We invited six mentors, three of whom accepted.✓Правильный ответ
I tested five batteries, two of which were flat.✓Правильный ответ
They hired eight guides, several of which spoke Arabic.
She reviewed four plans, none of whom met the limit.
Объяснение
Whom correctly refers back to the mentors, and which correctly refers back to the batteries. Guides are people and therefore cannot take of which here, while plans are things and cannot take of whom.