The problem with this question (it seems to me) is that it was likely written by someone who might not have an understanding of how pension plans work, if at all. Then others, who have more experience with this kind of thing, look at the question and get confused.
Commit makes more sense to me in terms of a company pension plan, that needs regular contributions so retired beneficiaries can keep getting paid. On the other hand, the wording makes it sounds like everything is optional - employees can pick the percentage they contribute, and the phrase employees are encouraged implies that they can opt out entirely. This sounds odd to me, as I belong to a company pension plan. I have no choice in the matter - my contributions are mandatory, and are a fixed percentage of my salary.
Submit makes sense in the case of one's own retirement plan. A friend of mine has a private registered pension fund, which her employer contributes to, as a benefit. She can choose to contribute a percentage of her salary every year, and the company matches a portion of that. Submit makes sense here, but then again, she isn't submitting funds to the (in general) retirement fund; it's her (specific) retirement fund.