The time taken for a stone dropped from rest to fall vertically through 16 m is 2.0 s. Based on these measurements, what is the best estimate for the acceleration of free fall?

A.     $4.0{\text{ m}}\,{{\text{s}}^{ - 2}}$

B.     $8.0{\text{ m}}\,{{\text{s}}^{ - 2}}$

C.     $9.8{\text{ m}}\,{{\text{s}}^{ - 2}}$

D.     $10{\text{ m}}\,{{\text{s}}^{ - 2}}$

B