Which type of drug is effective in stopping bacterial growth?

The type of drug that is effective in stopping bacterial growth is an antibiotic. Antibiotics work by targeting specific functions or structures in bacteria, which effectively inhibits their growth or kills them outright. For instance, some antibiotics disrupt the synthesis of bacterial cell walls, leading to cell lysis, while others may inhibit protein synthesis or nucleic acid synthesis, all of which are vital processes for bacterial proliferation.

This action makes antibiotics vital in treating bacterial infections and preventing the spread of bacteria within the body. The other options, while important in their specific areas, do not serve this purpose. Anti-parasitic drugs are designed to eliminate parasites, behavior-modifying medications primarily focus on addressing behavioral issues in animals, and antihistamines work to alleviate allergic reactions by blocking histamines, but none of these categories directly stop bacterial growth.