IP address of a particular class B host is 152.45.32.14, 16 bits for network part and 16 bits for host part .
need to calculate the broadcast address of the subnet if the subnet mask is 255.255.240.0
class B so N N H H , mask is 255.255.240.0 now 240 = 128 + 64 + 32 + 16 ( 2nd octet)
128 64 32 16 8 4 2 1
1 1 1 1 0 0 0 0
now turn / flip all 0 into 1 in both 1st and 2nd octet and it become 1111 means 1 + 2 +4+8 = 15 in 2nd octet and in 1st octet 1111 1111
now add 15 with 32 ( from ip address host 2nd octet) and it becomes 15 + 32 = 47
so the broadcast address of host 152.45.32.14 is 152.45.47.255
152.45.47.255 is option A hence it is the answer.