2) The president of the Women's Freedom Association tried to convince her peers they should join forces to prevent discrimination in the workplace rather than continuing to be underpaid.

(A) they should join forces to prevent discrimination in the workplace rather than continuing to be underpaid.
(B) that they should join forces to prevent discrimination in the workplace rather than continue to be underpaid.
(C) about joining forces to prevent discrimination in the workplace instead of continuing to be underpaid.
(D) for the joining of forces to prevent discrimination in the workplace rather than continue to be underpaid.
(E) to join forces to prevent discrimination in the workplace rather than continuing to be underpaid.

[spoiler]
OA - B[/spoiler]

I have some doubts in the PA
- Is 'that' essential. I feel no
- Is the usage of should correct. The correct is - convince X to do Y or convince that X do Y. Am I wrong?

With these, I marked C