Can we apply two different rules on the same line of a proof?

a$.$

No$,$ since each line can only apply a single rule.

b$.$

Yes, since some rules are only valid when they are applied simultaneously with another rule.

c$.$

Yes, and it is often a good idea to do this, since it makes the proof more efficient.

d$.$

No$,$ but we can apply the same rule twice on one line of the proof.

e$.$

Yes, as long as the two rules are different from each other.