Anetwork on the internet has a subnet mask of 255.255.240.0.what is the maximum number of hosts it can handle?

4094 hosts

Explanation:

In a network,

     Number of hosts is (2^host no -2)

We have subtracted 2 because out of these hosts two are used in broadcasting and other purposes.  

Host number is equal to the 0's in the Subnet mask

                    255.255.240.0

convert this into binary number i.e

   11111111.11111111.11110000.00000000

So,12 0's are there

           Number of valid hosts= 2^12 -2

                                                = 4096-2

                                                =  4094

i think the answer is b.