The correct answer is a) Systemic acquired resistance
Explanation:
In biology, systemic acquired resistance occurs as one organism develops resistance to a specific pathogen such as a virus or bacteria, this means, the organism's system recognizes previous pathogens it has been exposed to and in this way responds appropriately. The systemic acquired resistance occurs mainly in plants and due to this, it is believed this response is similar to one of the immune systems in animals. Therefore, the mechanism that is the closest process plants have to an immune system is Systemic Acquired Resistance or SAR.