Question 11
What makes a fatty acid a saturated fatty acid?
The right answer is the one marked above.
Every carbon atom in it is bonded to the maximum number of hydrogen atoms it can hold — it is saturated with hydrogen. These are solid or semi-solid at room temperature.
An unsaturated fatty acid does not carry that maximum, and it is liquid at room temperature. Read the two definitions side by side and the naming makes sense — "saturated" means full.