[单选题]
Suppose that an 80-kg person walkinh8(qbqj;ks .c g 58ahsg65w ypwceh.czkr*4ueu-s. 1 u on crutches supports all his weight on the two crutch tips, each of which is circular with a diamete5w k.ehap5hsu rcezgu1y-*8c.w4s 6ur of 4.0 cm. What pressure is exerted on the floor?
A. $78 \; kPa$
B. $156 \; kPa$
C. $312 \; kPa$
D. $624 \; kPa$
