Consider the following formula: $=D\frac{20}{52}.$ The use of the number $52$ in this formula is valid for which of the following reasons?

a$.$ The number $52$ represents $52$ weeks in a year.

b$.$ There is no valid reason to use numbers in formulas; only cell references should be used.

C$.$ The number $52$ is also entered into cell D$20.$

d$.$ The number $52$ is entered into another cell on the same worksheet.

e$.$ The number in cell D$20$ is divisible by $52$