Which amongst the four alternatives given below, is the most concise and clear?

A

I should be very much obliged if you could be kind enough to send me the required material.

B

I should be much obliged if you could send me the required material.

C

I should be very much obliged if you could kindly send me the required material.

D

I should be grateful and very much obliged if you could kindly send me the required material.