The main difference between a seed and a fruit is that a fruit

Analyze the question: We're asked for the main difference between a fruit and a seed. A fruit is the ripened ovary of a flower, and a seed is the ripened ovule inside it.

Key concept: scars

• A fruit forms from the ovary. It carries two scars: the style scar (where the style was attached) and the stalk (pedicel) scar (where it was attached to the plant).
• A seed forms from the ovule. It carries only one scar: the hilum (where it was attached to the ovary wall by the funicle). It also has a micropyle, but this is a pore, not a scar.

Checking each option:

• A. Size: Wrong. Some fruits are tiny and some seeds are large (e.g. coconut, a large seed in some contexts). Size is not a reliable distinction.
• B. Two scars vs one: Correct. A fruit has a style scar and a stalk scar, while a seed has only the hilum.
• C. Pigmentation: Wrong. Many seeds are coloured (e.g. red Abrus seeds), and some fruits are green or colourless.
• D. Dispersal by animals: Wrong. Both fruits and seeds can be dispersed by animals, so this does not separate them.

Answer: B

(The wording "a seed is has one" is a typo in the question, but the meaning is clear.)

Exam tip: Remember "Fruit = Two scars, Seed = one scar (hilum)." Fruit: style scar + stalk scar. Seed: hilum only.