The radicle

is the first part of a seedling to emerge from the seed during the process of germination. It is the embryonic root of the plant and grows downward in the soil. Hence, the correct answer is 'Radicle'.

What develops into a root on germination?

In botany, the radicle is the first part of a seedling (a growing plant embryo) to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant, and grows downward in the soil (the shoot emerges from the plumule).

What develops first in the process of germination from the seed?

The first step in the seed germination is imbibition i.e. absorption of water by the dry seed. Imbibition results in swelling of the seed as the cellular constituents get rehydrated. The swelling takes place with a great force. It ruptures the seed coats and enables the radicle to come out in the form of primary root.