Which of the following describes someone who is old and feeble?

The term "decrepit" specifically refers to someone who is old and feeble, often characterized by decrepitude, fragility, and a general decline in physical condition due to age. It conveys the idea of deterioration and weakness associated with old age, making it a precise descriptor for individuals who are aging and experiencing physical limitations or frailty.

In contrast, the other options do not relate to age or physical weakness. "Apprehensive" describes a feeling of anxiety or fear about future events. "Compatible" refers to the ability of two or more things to exist or work together harmoniously. "Ingrate" denotes a person who is ungrateful, emphasizing a lack of gratitude rather than age or frailty. This context highlights why "decrepit" is the most fitting choice among the available options.