Which pesticide is effective against organisms like caterpillars, beetles, and aphids?

The correct choice is insecticide because it specifically targets and controls insect pests that can cause damage to plants, such as caterpillars, beetles, and aphids. Insecticides contain active ingredients that disrupt the biological functions of insects, leading to their death or making it difficult for them to feed and reproduce. They are crucial in managing pest populations that threaten crops and ornamental plants, effectively protecting plant health and agricultural yield.

In contrast, acaricides are designed to control mites and ticks, which are not the primary concern when dealing with caterpillars, beetles, or aphids. Molluscicides are effective against mollusks like snails and slugs, thus irrelevant to the insects mentioned. Herbicides are formulated to target unwanted plants or weeds, again not applicable to insect pests. Therefore, insecticide is the appropriate choice for addressing the specified organisms.