[steps to apply] or [steps to applying]

I have made up the sentences below.

(1a) These are the steps to apply for financial aid.

(1b) These are the steps to applying for financial aid.

(2a) What are the steps to apply for financial aid?

(2b) What are the steps to applying for financial aid?

I have seen both forms of "apply" when it is used with "steps"? Which one is correct? Thanks a lot.