Computer Science Principle of Programming Languages.

Consider the following grammar:

$S$::$=AB|c$

$A$::$=aA|a$

$B$::$=b$

and the following derivation:

$S=>$ABC

$=>$aABC

$=>$aaBc

$=>$aabc

Which of the following are true?

This is a leftmost derivation

This is a rightmost derivation

This is not a valid derivation

This is a valid derivation, but it is not leftmost nor rightmost