The loudness L of sound in decibels is given by L=10log(I/I0) where I is the intensity of the sound, and I0 is the intensity of the least audible sound. If I0=10^-12 W/m^2 about how many times more intense is a 97 decibel sound than a 93 decibel sound?

A. 4.5
B. 1.5
C. 2.5
D. 3.5