Answer:
b. accelerated by intensive agricultural activity in arid and semiarid lands.
Step-by-step explanation:
Desertification is said be the degradation of land caused by natural processes or human activities. Climates variation and human activities are two main cause of desertification.
Human activities like deforestation , overgrazing and intensive agricultural activities can cause desertification in a vulnerable ecosystem like the arid and semi arid area. This intensive farming depletes the soil fertility and causes a strain to the already fragile ecosystem(arid and semi arid).
Humans over exploits the limited nutrient available in this area(semi arid and arid) through intensive farming causing an unbalance ecosystem. The dry land are further degraded by this human activities causing desertification.
Generally, desertification is accelerated by intensive agricultural activities.