Which of the following grammars are ambiguous?

GATE · 2026 · CS · Set 2 · Computer Science & IT

1. A.

   𝑆 → 𝑎𝑆𝑏 | epsilon

2. B.

   E→ 𝐸 + 𝐸 | 𝐸 ∗ 𝐸 | 𝑖𝑑

3. C.

   S→ 𝑎𝑆 | 𝑆𝑎 | epsilon

4. D.

   S → 𝑎𝑆 | epsilon

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