Asingle-line acl has been added to a router configuration using the command "ip access-list 1 permit 172.16.4.0 0.0.1.255".
the configuration also includes the "ip access-class 1 in" command in vty configuration mode.
which answer accurately describes how the router uses acl 1?

a. hosts in subnet 172.16.4.0/23 alone can telnet into the router.
b. cli users cannot telnet from the router to hosts in subnet 172.16.4.0/23 alone.
c. hosts in subnet 172.16.4.0/23 alone can log in but cannot reach enable mode of the router.
d. the router will only forward packets with source addresses in subnet 172.16.4.0/23.