What is a major difference between saturated and unsaturated fats?

A) At room temperature, saturated fats are liquid and unsaturated fats are solid.
B) Unsaturated fats have a flat molecular structure, but saturated fats are kinked.
C) Saturated fat molecules are packed together loosely, but unsaturated fats are tightly packed.
D) Unsaturated fats contain carbon-to-carbon double bonds, but saturated fats don't.