Which herbicides are categorized under growth regulators?

The correct categorization of growth regulators is represented by the specific chemicals listed in the selected choice, which includes 2,4-D, MCPA, MCPP, and Banvel. These herbicides are classified as auxin-type herbicides, which are growth regulators that mimic the natural plant hormone auxin. They work by disrupting normal plant growth processes, particularly affecting broadleaf plants while generally leaving grasses unharmed.

Auxins play critical roles in plant growth and development, influencing processes such as cell elongation, root formation, and flower development. By using synthetic auxins, these herbicides effectively control undesirable vegetation by promoting uncontrolled growth that leads to the plant's demise or severe stress.

In contrast, the other presented choices consist of herbicides that do not primarily act as growth regulators. For example, glyphosate is a non-selective systemic herbicide targeting broad-spectrum weed control, while diquat and pendimethalin each have distinct mechanisms unrelated to growth regulation. The remaining options also contain herbicides with modes of action that differ from those associated with growth regulation. This differentiation is essential for understanding herbicide application and management in agricultural or landscaping practices.