What does an accumulator specifically do in code?

An accumulator serves a specific function in programming, which is to sum values incrementally. This means that it holds a running total of numbers as they are processed within a program. When values are added to the accumulator, it updates its stored value by adding the new input to the previous total. This functionality is essential in scenarios where a cumulative total is required, such as in calculating totals in a financial application, aggregating scores, or compiling data metrics over time.

In contrast, the other options describe different operations that an accumulator does not perform. While constant values might be stored in variables, that is outside the scope of what an accumulator does. Generating a random selection refers to producing random outputs, which is distinctly different from accumulating totals. Tracking user input involves recording what a user enters into a program but does not inherently involve summing or accumulating values. Therefore, the primary role of an accumulator is to facilitate incremental summation, making option B the correct choice.