The secondary growth of a plant happens in the vascular cambium. When the vascular cambium produces more tissues, it produces secondary xylem cells and secondary phloem cells. This growth makes the stems thicker over time. Therefore, I, II, and III are all correct.

E. I, II, and III

Choices B, C, D, and E are all incorrect. When the plant pumps ions into the cells found in the roots, the water moves across the cortex and into the vascular cylinder through a process called osmosis.

A. The ions allow water to enter the roots by osmosis.

Choices A, B, C, and E are incorrect. The hormones called auxins trigger the cell elongation in stems. These hormones are involved in phototropism. The stem that is not exposed to the sunlight collects more amount of auxin. This event causes the shady side of the stem to curve because it grows faster than the other side.

D. Auxin stimulates cell elongation on the shady side of the stems.

Choices A, B, D, and E are incorrect. To avoid the decrease in biodiversity due to modern agricultural practices, seed banks must be established. In this way, the genetic diversity of plant species are preserved, particularly the wild relatives of crop species.

C. establishing a seed bank to preserve wild relatives of farm crops