stuck. please show work and explain.

Consider the topology shown below. There are three subnets with hosts (Subnets A, B, and C), and three subnets connecting the routers (Subnets D, E, and F). Assign network addresses to each of the subnets, using the network number and subnet mask with the slash notation, using the following constraints: All addresses must be allocated from 216.32.254.0/23. Subnet A should have enough addresses to support 250 interfaces. Subnet B should have enough addresses to support 120 interfaces. Subnet C should have enough addresses to support 60 interfaces. Subnets D, E,and F should have just enough addresses to support only 2 interfaces each. Assign the network numbers to the subnets in sequential order (A through F), starting with the first available range of addresses. Hint: The network number for Subnet A should be 216.32.254.0. What is the network number and subnet mask for Subnet B? Subnet A (250 interfaces) Subnet F Subnet D Subnet E Subnet C (60 interfaces) Subnet B (120 interfaces) Select one: a. 216.32.254.254/24 O b. 216.32.255.0/24 O c. 216.32.255.120/25 O d. 216.32.255.0/25