[单选题]
Human reaction time is usualli0.lz bye2- (e/zivmg y greater than 0.1u1*v6s 9i dtse0 s. If your friend holds a ruler between your fingers and releases it without warning, how far can you expect the ruler to falust*1i s69ev dl before you catch it?
A. at least 3.0 cm
B. at least 4.9 cm
C. at least 6.8 cm
D. at least 9.8 cm
