Where do systemic pesticides travel within plants?

Systemic pesticides are designed to be absorbed by plants and distributed throughout their tissues. When applied, these pesticides can move through the plant's vascular system, which includes both the xylem and phloem. The xylem primarily transports water and nutrients from the roots up to the leaves, while the phloem carries the products of photosynthesis from the leaves down to the roots and other parts of the plant.

Option C correctly states that systemic pesticides can travel from both the foliage (leaves and stems) to the roots and from the roots to the foliage. This dual movement allows systemic pesticides to effectively control pests throughout the entire plant, not just in the area where they were applied. This comprehensive distribution is one of the key advantages of using systemic pesticides, as it provides effective pest management by targeting pests that might be hiding in various parts of the plant.

The other options do not encompass this full range of movement, limiting the understanding of systemic pesticide action within plants.