The material of a sphere of radius r is melted and recast into a hollow cylindrical shell of thickness a and outer radius b. What is its length assuming that no material is lost in recasting?
A. 4r³/3a(2a−b)
B. 4r³/3a(b+a)(b−a)
C. 4r³/3a(b−a)
D. 4r³/3a(2b−a)
