Final answer:
To reference the length of the loan in the financial loan calculation formula in cell B5, enter the cell C2 in the row input cell box.
Step-by-step explanation:
The student's question refers to inputting a cell reference for a formula related to financial loan calculations in a spreadsheet software, such as Microsoft Excel. Given the provided information, if the cell B5 contains a formula for loan calculations and the nper argument (which stands for the number of payment periods) needs a cell reference, then the reference to the length of the loan should be placed into a 'row input cell box'. If cell C2 contains the value of the length of the loan, then you should enter C2 in the row input cell box to link the number of periods for the loan to the formula in B5.