Give an elementary matrix, E, that will carry out the row operation R_(3)->R_(3)-7R_(1). Test that
E actually works for carrying out this row operation. Which of the following options represents the correct matrix E?

A) [[ , , ], [ , 0, 0, ], [ , 0, 0, ], [ , 0, 0, 0]]
B) [[ , , ], [ , 0, 0, ], [ , 0, 0, ], [ , 0, 0, ]]
C) [[ , , ], [ , 0, 0, ], [ , 0, 0, ], [ , 0, 0, ]]
D) [[ , , ], [ , 0, 0, ], [ , 0, 0, ], [ , 0, 0, 0]]