Objective: How to store leftovers in a freezer

Which of the following solutions is more sound in terms of naive physics reasoning?

OPTIONS:
a). Place the leftovers in a tupperware or other container that can be sealed. Leave the contents unsealed and exposed. Place the container in the freezer.;
b). Place the leftovers in a tupperware or other container that can be sealed. Seal it with a lid or a sheet of plastic wrap. Place the container in the freezer.;
b).