Solve the Exponential Equation $21 = 2.78 \times 1.22 ^ { t }$

Solve the exponential equation $21 = 2.78 \times 1.22 ^ { t }$

A) $t = 9.74$
B) $t = 14.93$
C) $t = 10.17$
D) $t = 10.32$