Exp) Option b is the correct answer.

Lake Faguibine in northern Mali( in Africa started to disappear after catastrophic droughts in the 1970s. Over several  years, droughts in the 1970s dried up the lake..

The lake was once one of the largest in West Africa used to be fed by annual flooding from the Niger River.

The Lake Faguibine System, four interlinked lakes west of Timbuktu in Mali, was historically one of Mali’s most fertile areas.

Source: https://www.unep.org/news-and-stories/story/benefits-galore-if-malis-lake-faguibine-system-were-revived-0

https://earthobservatory.nasa.gov/images/8991/drying-of-lake-faguibine-mali

https://www.africanews.com/2021/10/27/climate-change-clears-mali-s-lake-faguibine-displaces-population//