[单选题]
A string of mass m and length L is under tension T. Th 1s4yjr; dhumpgy/ *m2w 5,qyhe speed m8u6 hgyiwg(( of a wave in the string is v. What will be the speed of a wave in the string (g8wyhm(ugi 6 if the length is increased to 2L, with no change in mass?
A. $0.5 \; v$
B. $0.71 \; v$
C. $1.4 \; v$
D. $2 \; v$