What effect does the following command have on TCP packets?

What effect does the following command have on TCP packets?

iptables- A INPUT d 10.142.232.1 p tcp –dport 20:21 j ACCEPT
A . Forward all TCP traffic not on port 20 or 21 to the IP address 10.142.232.1
B . Drop all TCP traffic coming from 10.142.232.1 destined for port 20 or 21.
C . Accept only TCP traffic from 10.142.232.1 destined for port 20 or 21.
D . Accept all TCP traffic on port 20 and 21 for the IP address 10.142.232.1

Answer: D