[单选题]
Suppose that an 80-kg j rt+ kvje7yi*7.jvmw :uq5c;p21zyos7 a04xi6bdeb4 2ghj*phr-x eaerson walking on crutches supports all his weight on the two crutch tips, each of which is circular with a diameter of 4.0 cm. What pressure is exerted on y-*asj d2 bhg4p1b0raxz h4e2ie7xo6 the floor?
A. $78 \; kPa$
B. $156 \; kPa$
C. $312 \; kPa$
D. $624 \; kPa$
