The most prevalent form of weathering in hot-tropical desert areas is likely to be mechanical weathering. Mechanical weathering, also known as physical weathering, is the process of breaking down rocks into smaller pieces without any change in the chemical composition of the rocks. This type of weathering is common in desert areas due to the extreme temperature fluctuations and high levels of solar radiation.

Option 1: Mechanical weathering is the correct answer. It includes processes such as thermal stress, frost wedging, and abrasion, which are all common in hot-tropical desert environments.

Option 2: Chemical weathering involves the decomposition and alteration of rocks through chemical reactions. While chemical weathering does occur in desert areas, it is typically less prevalent compared to mechanical weathering.

Option 3: Biological weathering refers to the breakdown of rocks by living organisms, such as plants and animals. While plants and animals do exist in desert areas, the harsh conditions make biological weathering less prevalent compared to other forms of weathering.

Option 4: Leaching is a process where minerals are dissolved and carried away by water. While leaching can occur in desert areas, it is also less prevalent compared to mechanical weathering.

Therefore, the correct answer is option 1 (mechanical