Are both versions of each of these sentences correct?

In all of the following sentences, is it ok to use both versions?

1) a) All he wanted to do was cry.

b) All he wanted to do was to cry.

2) a) All he wanted was to cry and yell.

b) All he wanted was to cry and to yell.

Is it ok to omit the "to" of infinitives in a sentence if the first one already has it?

3) a) Sometimes, all it takes is keeping one's mouth shut.

b) Sometimes, all it takes is to keep one's mouth shut.

4) a) Sometimes, to keep one's mouth shut is the only option.

b) Sometimes, keeping one's mouth shut is the only option.