When a plant encounters a pathogen, it initiates a series of complex signaling pathways that may result in being able to fend off future attacks by the same pathogen. this mechanism may be the closest process plants have to an immune system. which of the following describes this process?
a) systemic acquired resistance
b) herbivore-induced plant volatility
c) reactive oxygen species generation
d) chromatin modification.

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.

they may bind directly to special “promoter” regions of dna, which lie upstream of the coding region in a gene, or directly to the rna polymerase molecule.

i'd say that the moon rock is about 2.2 billion years old.