16. Anna and Bonnie are racing on a 400-meter oval track. They start at the same time, but Anna is ahead because she is 25% faster than Bonnie. Then Anna will have run ( ) laps when she first overtakes Bonnie.
(A) $\frac{5}{4}$
(B) $\frac{10}{3}$
(C) 4
(D) 5
(E) 25
16. D.

Since Anna is 25% faster than Bonnie, when Bonnie finishes the first lap, Anna has run an additional $\frac{1}{4}$ lap. Thus, when Bonnie completes 4 laps, Anna has run an extra full lap. This means that when Anna completes 5 laps, she overtakes Bonnie for the first time.