Which one of the following grammars is free from left recursion?

• A. S → ABA → Aa | bB → c
• B. S → Ab | Bb | cA → Bd | ϵB → e
• C. S → Aa | BA → Bb | Sc | ϵB → d
• D. S → Aa | Bb | cA → Bd | ϵB → Ae | ϵ