Three Solid Objects of the Same Material and of Equal

Multiple Choice

Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for

A) Cube
B) Cylinder
C) Sphere
D) Equal for all the three