I would choose (c) almost every time in a rec league.There's no exact "name/label" for what this league is that I coach in. We can do a couple of things with our lineups:
a.) Bat 10/field 10 with listed substitutes
b.) Bat 10/field 10 with a DP/Flex (and listed substitutes if available)
c.) Bat everyone in the lineup and free-substitute players on the field at any time.
I typically do (a.) or (b.) because I have some bats on this team that need serious work that can't handle this league, and it's hard for them in a game situation. So usually I play them as a Flex with a stronger bat covering them, and they usually understand and embrace what role they are given. "F" in this case is one of those weaker bats, hence why she is generally a Flex.
I would change that for discipline problems and for elimination playoff games.