Answer: The frequency of index tracking

## Explanation **Option B is correct** because the frequency of index tracking itself is not a source of tracking error. Most ETFs track their indices on a continuous basis throughout the trading day, and this frequency doesn't inherently create tracking error. **Option A is incorrect** because representative sampling (holding only a subset of index securities) is a common source of tracking error. **Option C is incorrect** because holding depositary receipts instead of actual index constituents can create tracking error due to differences in pricing, liquidity, or other factors between the receipts and the underlying securities.

Author: LeetQuiz Editorial Team