Which one of the following regions in plants is responsible for the growth of its roots and shoots?

The growth of a plant's roots and shoots is primarily driven by the apical meristem. Meristematic tissues are specialized regions of active cell division, and apical meristems specifically occur at the growing tips of roots and shoots [1]. These tissues consist of undifferentiated cells that divide continuously to produce primary tissues, enabling the plant to extend in length—a process known as primary growth. The shoot apical meristem is responsible for the elongation of the stem and the formation of leaves, while the root apical meristem occupies the tip of the root, facilitating its growth through the soil [1]. In contrast, collenchyma provides mechanical support, the endodermis regulates nutrient uptake in roots, and the cortex serves as a storage and transport layer, but none are responsible for the primary longitudinal growth of the plant.

Sources

1. [1] https://www.ncbi.nlm.nih.gov/books/NBK10030/