Explanation:

- Emerald is known for its vivid and distinct color.

- An emerald's color ranges from a light green to deep, rich green.

- Option 1: Red is the color of rubies, not emeralds.

- Option 3: Blue fits sapphires, which are distinctly different from emeralds.

- Option 4: Yellow is more commonly associated with gems like citrine or yellow sapphires.

- Option 2: Green ?? is the correct answer since emeralds are universally recognized for their green hues.