Ella simplifies (3b+4r)+(-2b-r) and says the result is b+5r. What error did Ella make?

A. Ella incorrectly combined the b coefficients. The correctly simplified expression is 5b+5r.

B. Ella incorrectly combined the b coefficients. The correctly simplified expression is -b+5r.

C. Ella incorrectly combined the r coefficients. The correctly simplified expression is b-5r.

D. Ella incorrectly combined the r coefficients. The correctly simplified expression is b+3r.