CCNA 640-801 suppernetting question

Q. Which of the following /24 subnets can be supernetted intoa larger network.

A. 10.10.20.0/24 and 10.10.21.0/24 into 10.10.20.0/23

B. 10.10.21.0/24 and 10.10.22.0/24 into 10.10.21.0/23

C. 10.10.130.0/24,10.10.131.0/24, 10.10.132.0/24, and 10.10.133.0/24 into 10.10.130.0/22

D. 10.10.164.0/24, 10.10.165.0/24, 10.10.166.0/24, and 10.10.167.0/24 into 10.10.165.0/22

I feel the answer is A

It's all the answers but "C". I'll quiz you now, why is it not answer "D"?

the answer is not "D" because the supernetted address cannot be a odd address and since four networks are being supernetted the summarized address has to must be a multiple of four.

Sorry for my very confusing post, I had a typo, I meant "C". I am not the best at the explanation of this, but here it goes...

I do this in binary because you'll end of messing things up otherwise.

Supernetted network is 10.10.130.0/22

Network bits 00001010.00001010.10000.....Host bits 10.00000000

The size of the host bits I get from /22.

So if you zero out the host portion to get your network
00001010.00001010.10000 00.00000000

You'll get 10.10.128.0. So then you can find first and last hosts.
00001010.00001010.10000 00.00000001 = 10.10.128.1
00001010.00001010.10000 11.11111110 = 10.10.131.254

Back into relation with the question. The networks
10.10.130.0/24 (10.10.130.1 - .254)
10.10.131.0/24 (10.10.131.1 - .254)
10.10.132.0/24 (10.10.132.1 - .254)
10.10.133.0/24 (10.10.133.1 - .254)

Would exceed 10.10.130.0/22 because as you can see, 10.10.131.254 is last useable address, far below 10.10.133.254, the last useable address for 10.10.133.0/24.

Doing all of this in binary is the only way to go.

I have never seen it broken down that way. Every Cybex, Cisco press, and Prep Logic matarial I have read does not go into detail about how to supernet, Thanks. I'll give it a try!!!