what step will be most effective for a manufacturer that wants to reduce the human cost of extracting the minerals it uses in its smartphones

The options are

committing to only mining minerals in the United States

decreasing the prices of its products

switching to using gold instead of tungsten in its products

verifying that child labor was not used in mining these minerals

The answer is verifying that child labor was not used in mining these minerals

Explanation:

The most effective for a manufacturer that wants to reduce the human cost of extracting the minerals it uses in its smartphones will be verifying that child labor was not used in mining these minerals.

If child labor which is against the government rules is used then the company is at a greater risk of being sued which could lead to huge fines at the detriment of the company.