An insect is at the bottom of a hemispherical ditch of radius 1 m. It crawls up the ditch but starts slipping after it is at height h from the bottom . If the coefficient of friction between the ground and the insect is 0.75 , then h is
a. 0.20 m
b. 0.45 m
c. 0.60 m
d. 0.80 m