The correct answer is Option 3: 1 and 3 only.

Drip irrigation is a method of providing water to crops by applying it directly to the roots of the plants in small, frequent doses. This method has several advantages, including:

1. Reduction in weed: Drip irrigation provides water only to the plants, which reduces the growth of weeds. This is because weeds require more water than crops and are unable to access the limited water supply provided by drip irrigation. Furthermore, drip irrigation systems reduce the amount of water that is applied to the soil surface, which reduces the germination of weed seeds.

2. Reduction in soil salinity: While drip irrigation does not directly reduce soil salinity, it does help to manage it. This is because drip irrigation delivers water directly to the plant roots, which reduces the amount of water that is lost through evaporation or runoff. As a result, less salt accumulates on the soil surface, which reduces the risk of soil salinization.

3. Reduction in soil erosion: Drip irrigation applies water directly to the soil, which reduces the amount of water that is lost through surface runoff. This helps to prevent soil erosion, which can lead to the loss of soil fertility and the degradation of the soil structure. In addition, drip irrigation systems are designed to deliver water slowly and steadily, which helps to reduce the amount of soil that is displaced by the water.

It is important to note that while drip irrigation has many advantages, it is not a perfect solution. For example, it can be expensive to install and maintain, and it may not be suitable for all crops or soil types. Additionally, drip irrigation systems require regular maintenance to ensure that they are working properly and delivering water evenly to all plants. Despite these limitations, drip irrigation is a highly effective method of providing water to crops, and it has become increasingly popular in many parts of the world.