VLSM question Tricky from learncisco.net

Question: You are implementing a VLSM network. You are using the Class A network of 10.0.0.0/8 and need to create networks that support 254 hosts that will be used for each LAN. The tenth network that was created will be used for addressing all the point-to-point links between routers at HQ, all the point-to-point WAN links, and any point-to-point links in the branch offices.

What is the subnet ID of the second point-to-point network created?
A. 10.0.9.8/30
B. 10.0.9.2/30
C. 10.0.9.6./30
D. 10.0.9.4/30
E. 10.0.10.4/30
F. 10.0.10.2/30

Correct answer: D

Explanation :

10.0.0.0/8
since 254 hosts are required mask is /24
tenth network is 10.0.9.0/24

this network again subnetted with /30

give 10.0.9.4 as the second network.