The prolonged drought had a _____ effect on agricultural yields, leading to widespread food shortages and economic distress in the region, affecting millions of livelihoods.

✓ Correct Answer: Option C

The drought led to 'widespread food shortages and economic distress,' indicating a harmful or damaging effect. 'Deleterious' means causing harm or damage. 'Salubrious' and 'propitious' mean favorable or healthy, and 'benign' means gentle or harmless, none of which fit the negative context.