Which of the following human activities contributed to worsening soil degradation in Sahel in 1970s and 1980s

The question seems to be incomplete as there are no options provided. However, I can provide some general information on the human activities that contributed to worsening soil degradation in Sahel in the 1970s and 1980s:

1. Overgrazing: This is when the population of livestock exceeds the carrying capacity of the land, leading to overgrazing. The vegetation is consumed faster than it can regrow, leading to soil erosion and degradation.

2. Deforestation: The cutting down of trees for timber and to clear land for agriculture can lead to soil degradation. Trees help to hold the soil together and their removal can lead to increased erosion.

3. Unsustainable farming practices: This includes practices such as monoculture (growing a single crop over a large area for many years), which can deplete the soil of certain nutrients, and the excessive use of chemical fertilizers and pesticides, which can harm the soil's natural fertility.

4. Population pressure: Rapid population growth can lead to increased demand for food and other resources, leading to overexploitation of the land and soil degradation.

5. Climate change: Changes in climate patterns, such as reduced rainfall and increased temperatures, can exacerbate soil degradation.

These activities led to a severe environmental crisis in the Sahel during the 1970s and 1980s, known as the Sahel drought.