A contraction of surface active agents; substances that allow oil and water to mix, or emulsify

• A. Detergents
• B. Surfactants
• C. Emulsifiers
• D. Coagulates

Answer: (B)

Surfactants are surface-active agents. They lower the surface tension between two liquids, such as oil and water, so they can mix and form emulsions. Their molecules have a water-attracting head and an oil-attracting tail, so they position themselves at the oil–water interface or assemble into micelles, allowing oil droplets to be dispersed in water and stabilized. This exact description matches the idea of substances that enable oil and water to emulsify, making the correct choice surfactants. Detergents are a type of surfactant used for cleaning, emulsifiers stabilize emulsions (a related function but more specific), and coagulates means to clump or clot, which isn’t about emulsifying.