[单选题]
A rectangular garden measur0+ w( emuf:fpa(o7l hwes 15 m long and 13.7 m wide. What is txe 6a86ea gd(rhe length of a diagonal from one corner of the garden to the otd8 gx r(aee66aher?
A. $18 \; m$
B. $19 \; m$
C. $20 \; m$
D. $21 \; m$
E. $4.1 \times 10^{2} \; m$
