Given data

• Positive zero error $= 0.2\,\text{mm}$
• Least count $= 0.01\,\text{cm}$
• Main scale reading: since vernier zero lies between $8.5\,\text{cm}$ and $8.6\,\text{cm}$, $\text{MSR} = 8.5\,\text{cm}$
• Vernier coincidence $= 6$

Observed reading Vernier contribution is: $\text{VSR} = 6 \times 0.01 = 0.06\,\text{cm}$

So the observed reading is: $\text{Observed reading} = 8.5 + 0.06 = 8.56\,\text{cm}$

Zero error correction Positive zero error means the instrument reads more than the actual value. Hence correction is subtracted.

Convert zero error into cm: $0.2\,\text{mm} = 0.02\,\text{cm}$

Therefore, $\text{Correct reading} = 8.56 - 0.02 = 8.54\,\text{cm}$

Final answer $\boxed{8.54\,\text{cm}}$

Option check

• A: $8.58\,\text{cm}$ ❌
• B: $8.54\,\text{cm}$ ✅
• C: $8.56\,\text{cm}$ ❌
• D: $8.36\,\text{cm}$ ❌