A Penetration Tester Is Attempting to Open a Socket in a Bash

A penetration tester is attempting to open a socket in a bash script but receives errors when running it. The current state of the relevant line in the script is as follows: Which of the following lines of code would correct the issue upon substitution?

A) open 0<>/dev/tcp/${HOST}:${PORT}
B) exec 0C) exec 0D) exec 3<>/dev/tcp/${HOST}/${PORT}
E) open 3F) open 3