Values in a function:

A. must be spelled out in words, not numbers
B. must be entered as whole numbers.

c. Can be a cell or a range of cells

D. Cannot have a negative value.

To determine the correct answer, we can analyze each option:

A. "Must be spelled out in words, not numbers." This is not true. In most cases, values in a function can be represented as numbers. For example, in a mathematical function like "SUM(1, 2)", the numbers 1 and 2 are accepted as values.

B. "Must be entered as whole numbers." This is not always the case. In many functions, values can be decimals or fractions. For instance, in the function "AVERAGE(1.5, 2.5)", the decimal numbers 1.5 and 2.5 are valid values.

C. "Can be a cell or a range of cells." This option is correct. In many functions, you can use cell references or ranges instead of manually entering values. For example, in the function "SUM(A1:A5)", the range A1:A5 is accepted as a value.

D. "Cannot have a negative value." This is not true either. Negative values are perfectly acceptable as input for many functions. For instance, in the function "MAX(-1, -5, -10)", the negative numbers -1, -5, and -10 are valid values.

So, based on the analysis, the correct answer is option C. Values in a function can be a cell or a range of cells.