Answer D was added to demonstrate a common typographical in assigning a subnet mask. This leaves 14 variable bits in the network portion of the address- all the bits in the second octet, and the six least significant bits of the first octet. Two to the 14th power is approximately 16,000, which is the approximate number of unique class B networks available. Short answer is correct. Short answer is correct.
Short answer is correct.
Short answer is correct. Short answer is correct.