Which of the following is a colourless gas with the smell of rotten eggs?

Hydrogen Sulphide (H2S) is a colourless, toxic gas that smells like rotten eggs, which is a characteristic odour making it easily identifiable. It is naturally found in crude petroleum, natural gas, volcanic gases, and hot springs. Exposure to hydrogen sulphide in high concentrations can be hazardous to human health, potentially leading to respiratory issues and even death.