1) a, you write class Foo { ... }
2) c, a constructor does not have a return type
3) d, every instance gets its own copy
4) b, a reference variable. Ofcourse, an instance or class variable may or may not be a reference variable.
5) c, the new keyword instantiates objects.
Since the ARP broadcast is utilized to request the MAC address of the Host with the IP address contained in the ARP, the PC needs to know the destination of MAC address before it can produce the frame header for the particular PING requested, before it can send a PING to a host.