Concept:Identification of a historical lake in Hyderabad.Explanation:Gandipet lake, a significant water source for Hyderabad, is also known by another name. This lake was constructed by the sixth Nizam, Mir Mahboob Ali Khan, after the severe flood of 1908. It is a popular picnic spot situated about 20 km west of Hyderabad. The other name for Gandipet lake is Osman Sagar.Answer:A. Osman Sagar