Which of the following conditions would be the worst for the dispersion of H2S?

Correct Answer: Option A — nearly calm, clear nights or early morning

H2S is heavier than air and tends to settle in low-lying areas. Calm, clear nights or early mornings lack the thermal turbulence and wind mixing necessary to disperse the gas. Under these stable atmospheric conditions, H2S can accumulate in dangerous concentrations, creating a significant hazard for personnel on deck.