Assertion (A) : Phenyl is used as a household germicide. Reason (R) : Phenyl is a phenol derivative and phenol is an effective germicide.

The correct answer is Option 1.

Assertion (A) is true because "Phenyl" (commercial name for liquid disinfectants) is universally used in households to sanitize floors and toilets due to its potent antimicrobial properties.

Reason (R) is also true and provides the correct scientific basis for the assertion. Phenyl is a derivative of phenol (carbolic acid). Phenol was the first antiseptic used in surgery. It works by denaturing bacterial proteins and disrupting cell membranes, making it an effective germicide. In household phenyl, substituted phenols or coal tar derivatives are emulsified with soap to create a disinfectant that retains these germicidal properties while being safer for domestic handling.

Since the germicidal efficacy of phenyl is directly derived from its phenolic chemical structure, R is the correct explanation of A. Other options are incorrect as they fail to acknowledge the direct causal link between the chemical nature of phenol and the functional utility of phenyl.