The element is the entry in the 1st row and 3rd column of the matrix, which, in this case, is 7.
Edit: Got my rows/columns mixed up! Row 1, Column 3 is actually -1, as the original poster pointed out.
The row is the first number in a13. Rows go across. So you are in the top row.
The 3 or second number is the column. Columns go up and down.
Row 1 column 3 is the - 1.
The answer is C.
9.5m questions
12.2m answers
is the entry in the 1st row and 3rd column of the matrix, which, in this case, is 7.