Step 1: Understanding cell reference in Excel.
In MS Excel, cells are referenced by the column letter followed by the row number. Therefore, the reference for the cell in column A and row 4 is A4.
Step 2: Why other options are incorrect.
- (A) 4A is incorrect because the row number comes after the column letter in Excel.
- (C) AA is incorrect because it represents a cell in column AA, not column A.
- (D) 44 is incorrect because it does not follow the correct cell reference format.
Step 3: Conclusion.
The correct reference is A4.
Final Answer: A4.