-Salicylic acid is a naturally occurring chemical produced in willow trees.
Salicylic acid is used by humans in some acne products to kill bacteria that
cause skin irritation
Based on this information, what stimulus most likely causes willow trees to
increase the production of salicylic acid?
Freezing conditions that damages leaves
Changing seasons with less direct sunlight
Damage to the bark of the tree trunk
Exposure to pathogens in the vascular tissue