How would you do this?

You are logged in as user tux1, but now you want to switch to user tux2 using tux2’s environment.
How would you do this?

A.
su tux2

B.
su -e tux2

C.
su – tux2

D.
su -m tux2

E.
su -f tux2

Explanation:
from the man pages:
-, -l, –login Provide an environment similar to what the user would expect had the user logged in directly.
There are no -e or -f options and -m would not switch the environment (except PATH)