What is the difference between systemic and contact pesticides?

The correct answer highlights a fundamental distinction in how systemic and contact pesticides function. Systemic pesticides are designed to be absorbed by plants and then translocated throughout their tissues. This means that when pests feed on the plant, they ingest the pesticide, which can lead to effective control of the pest even if it does not come into direct contact with the pesticide application. This is particularly useful for targeting pests that may be hidden, such as those feeding on the plant's vascular system.

In contrast, contact pesticides operate by killing pests upon direct contact. They do not need to be ingested by the pests to be effective; rather, they disrupt physiological processes immediately upon application. Therefore, the action of contact pesticides is limited to the pests that come into direct contact with the treated surfaces at the time of application.

The other options either misinterpret the mechanics of these pesticide types or provide inaccuracies about their characteristics. Understanding this distinction is crucial for effective pest management strategies, as the choice between systemic and contact pesticides will depend on the specific target pest and its behavior, as well as the environmental conditions under which the treatment is applied.