Explanation:

Let's break down the statements and options:

- B is 200% efficient than A

- This means B is 3 times as efficient as A (A’s efficiency = x, B’s efficiency = x + 200%x = 3x).

- B is 50% efficient than C

- This means B is 1.5 times as efficient as C (C’s efficiency = y, B’s = 1.5y, so y = B/1.5 = 3x/1.5 = 2x).

- Efficiencies:

- A = x

- B = 3x

- C = 2x

- Total = x + 3x + 2x = 6x

- In 2 days, all together do: 2 × 6x = 12x (work done)

- Let total work = W.

- If A alone:

- A in 1 day = x

- W = 12x (from above, as in 2 days all finish it together, so W = 12x)

- So, A needs 12 days to finish it alone.

Relevant calculation for options:

1. 10 days

2. 12 Days

3. 4 days

4. 6 days

5. 8 days

Correct Answer:

Option:2- 12 Days