Which of the following part elongates directly and leads to the formation of primary roots?

The direct elongation of the radicle leads to the formation of primary roots which grows inside the soil. 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).