Correct Option: C. Drought and desertification Explanation of the Correct Answer:

1. Understanding Drought and Desertification:
2. Drought refers to a prolonged period of abnormally low rainfall, leading to water shortages. It can severely impact agriculture, water supply, and ecosystems.
3. Desertification is the process by which fertile land becomes increasingly arid and unproductive, often due to a combination of climatic changes and human activities such as deforestation, overgrazing, and poor land management.
4. Geographical Context of Nigeria:
5. Nigeria is divided into various climatic zones, ranging from the humid tropical regions in the south to the arid and semi-arid regions in the north.
6. The northern part of Nigeria, particularly areas like the Sahel region, is more susceptible to drought and desertification due to its climate, which is characterized by low rainfall and high temperatures.
7. Impact of Drought and Desertification in Nigeria:
8. The northern regions of Nigeria, such as Borno, Yobe, and parts of Kano, are particularly affected by these issues. The encroachment of the Sahara Desert has led to significant loss of arable land, affecting food security and livelihoods.
9. The consequences include reduced agricultural productivity, increased poverty, and displacement of communities as people migrate in search of better living conditions.

Why the Other Options are Incorrect: A. River Blindness: - River blindness, or onchocerciasis, is caused by a parasitic infection transmitted by blackflies. While it is a significant health issue in Nigeria, it is not geographically limited to a specific area like the northern regions affected by drought and desertification. It primarily affects riverine communities, which are not necessarily the same areas suffering from drought. B. Tse-tse Fly Infestation: - The tse-tse fly is known for transmitting sleeping sickness (trypanosomiasis) and is primarily found in the central and southern parts of Nigeria, particularly in areas with dense vegetation. While it poses a health risk, it does not correlate with the widespread environmental issues of drought and desertification that predominantly affect the northern regions. D. Toxic Waste Pollution: - Toxic waste pollution is a significant environmental issue in Nigeria, particularly in the Niger Delta region due to oil spills and industrial waste. However, this problem is localized and does not represent the broader environmental challenge of drought and desertification affecting large areas of the country, especially in the north. Summary of Key Points:

• Drought and desertification are critical issues in northern Nigeria, leading to loss of arable land and food insecurity.
• The geographical distribution of health issues like river blindness and tse-tse fly infestation does not align with the areas suffering from drought.
• Toxic waste pollution is a localized problem, primarily affecting the Niger Delta, not the broader northern regions.
• Understanding the climatic zones and their impacts is essential for recognizing the environmental challenges faced by different regions in Nigeria.