Insectivorous plants are adapted to grow in soil that is deficient in nitrogen. Nitrogen is an essential nutrient for plants as it is required for the synthesis of proteins and other important molecules. However, in nutrient-poor environments such as boggy areas or acidic soils, there may be a limited supply of nitrogen. Insectivorous plants have evolved to overcome this by capturing and digesting insects to obtain the nitrogen they need. This adaptation allows them to thrive in environments where other plants may struggle due to a lack of nitrogen. Therefore, option 2 is correct. It is important to note that while insectivorous plants may also require other nutrients like calcium, magnesium, and water, the given question specifically focuses on the nutrient deficient in the soil, which is nitrogen.