Answer : 3. "Ensuring safety and health at work in a changing environment"
Explanation :

Every year, International Workers' Day is observed on 1 May, which is celebrated across the world including India to honor the contributions of the labor movement. Beginning with the Chicago labor strike of 1886 demanding an eight-hour workday, it gained prominence after the Haymarket Incident. In 1889, leaders of twenty countries established it as International Labor Day. The 2024 theme focuses on workplace safety and health amid climate change, with an emphasis on the challenges faced by workers globally.