A diamond retailer is introducing a new stock taking system. Each diamond is assigned a
character that represents the colour. The valid domain for the character ranges from D to Z. The
colour is then graded using the following scale:

Which of the following test sets will provide the best equivalence partitioning coverage?

A.
D, F, G, H, K, M, N, P, T, Z

B.
D, G, K, N, S

C.
A, E, H, L, P, T, §

D.
E, H, L, M, U, €

Explanation: