Human rights violations most likely occur:

Human rights violations are most prevalent deep within supply chains, where oversight is weakest.

Why B (Deep in supply chains) is correct:

First-tier suppliers are often audited, while deeper tiers have less transparency.

Forced labor, child labor, and unsafe working conditions are more common in third-tier and informal supply chains.

Example: Textile industry abuses in subcontracted factories.

Why not A or C?

A is incorrect—first-tier suppliers face more scrutiny from brands.

C is incorrect—violations are even more likely in third-tier suppliers and beyond.