Naomi Has a Spreadsheet Set Up Listing the Different Members

Multiple Choice

Naomi has a spreadsheet set up listing the different members of the Art Museum, and the dues that they have paid. Please answer the two questions below.
-Naomi has the total dues paid for all members in cell D45. She wants to keep this cell reference the same, no matter where she copies it. She would then type a $ before the ____.

A) column letter ($D45)
B) row number (D$45)
C) both a. and b. ($D$45)
D) neither a. nor b. ( D45)