Question

what is metabolism?
the ability to reproduce cells
the ability to convert energy to a usable form
the ability to respond to the environment
the ability to maintain homeostasis

Explanation:

Metabolism refers to the set of chemical reactions in organisms. It mainly involves processes like converting food into energy (such as through cellular respiration where glucose is broken down to produce ATP - the usable form of energy for cells). Reproduction of cells is more related to cell - cycle processes like mitosis or meiosis. Responding to the environment is part of an organism's sensory and regulatory mechanisms (e.g., plants bending towards light). Maintaining homeostasis is a broader concept that metabolism contributes to but is not the direct definition. Metabolism's key aspect is energy conversion.

Answer:

the ability to convert energy to a usable form