Which prefix indicates a decrease in normal functioning?

The prefix that indicates a decrease in normal functioning is "brady-." This prefix is derived from the Greek word "bradys," meaning slow or slow down. In medical terminology, it is often used to describe conditions where there is a reduced rate of biological processes, such as bradycardia, which refers to a slower than normal heart rate. This reflects a decrease in the normal functioning of the heart's rhythm.

In contrast, "macro-" refers to something that is large or enlarged, which has the opposite connotation of increase rather than decrease. "Nephro-" pertains to the kidneys and is associated with kidney-related conditions, while "litho-" refers to stones or calculi, typically in reference to conditions involving stones in organs. These prefixes do not imply a decrease in normal functioning, thereby making "brady-" the correct choice for indicating a reduction in function.