Question $4(1$ point$)$

Gis said to be in Chomsky Normal Form if all its productions are in one of the following two forms: $ABC$ where $A,B,C$ are variables, or $A$a where $a$ is terminal. What else also is a requirement?

Ghas no useless symbols

$G$ has no unit productions

$G$ has no epsilon$-$productions

All of the answers