Explanation:

This year Mumbai and Hyderabad have been jointly recognised as ‘2021 Tree City of the World’ for their commitment to growing and maintaining urban trees and greenery in building healthy, resilient and happy cities.

• While Mumbai has made the list for the first time, Hyderabad has featured on it for the second consecutive year.

About Tree City of the World status Programme

• The Food and Agriculture Organization of the United Nations and the Arbor Day Foundation have developed this programme.
• It is to celebrate greener cities and towns worldwide.
• The Tree Cities of the World programme is committed to inspiring cities and towns to care for and celebrate their urban tree canopy.
• The aim of starting this programme was to recognise towns and cities across the globe that are committed to making sure that their trees and concrete forests are sustainably managed, properly maintained, and duly celebrated.
• Under this programme assistance, direction, and worldwide recognition is provided to those communities that are showing dedication to their urban forest. The programme also provides a framework for a sustainable and healthy urban forestry programme in a very city or a town.

Hence option 2nd is correct.