What type of damage does Rust cause to plants?

Rust is a fungal disease that affects a variety of plants and is known for causing significant damage. When rust infects plants, it results in symptoms such as discoloration of leaves, formation of pustules, and ultimately leads to wilting and leaf drop. The presence of rust can severely weaken plants, as it impairs their ability to photosynthesize effectively due to the damage inflicted on their foliage. This weakening can also contribute to a decline in overall plant health, making them more susceptible to other environmental stresses and diseases.

In contrast, the other options imply positive effects on plant health or growth, which is not the case with rust. It does not promote healthy growth or enhance fruit development, as instead, it detracts from the plant’s overall vigor. Additionally, rust does not increase a plant’s resistance to disease; rather, it compromises their defense mechanisms, increasing their susceptibility to further infections. Therefore, the primary effects of rust on plants are negative, leading to wilting and leaf drop, making option B the correct answer.