Question

1. Which are more important of the 10 activities?

2. Which are more important among the 10 activities?

3. Which is more important of the 10 activities?

4. Which is more important among the 10 activities?

(Which ones are grammatical? Are all grammatical?)

Answer 1

All are grammatically correct. 1 and 2 are requiring an answer in the plural. 3 and 4 require an answer in the singular.