Answer:a. when muscle mass increases
Explanation:according to health expert muscles increase will increase the rate at which your body burns calories even when you are at rest, your body continues to burn calories which increase the metabolism rate.
The ability of your body to digest food increases with muscle increase.
Metabolic rate increases when fat mass increases.
The metabolic rate increases with increasing weight, height and surface area.
Body composition: Adipose tissue has less metabolic activity than muscle tissue. As lean muscle mass increases, metabolic rate increases.
With this information, we can conclude that the metabolic rate increases when the fat mass increases.
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