Answer:
Autonomic nervous system prepares the body for the fight or flight response by increasing heart rate and blood pressure (option A).
Step-by-step explanation:
The increase in heart rate and blood pressure that occurs in the fight and flight response is due to increased blood levels of adrenaline, a neurotransmitter produced by the adrenal cortex. This response is mediated by the sympathetic autonomic nervous system.
Usually, the stimulus that triggers this reaction of fight and flight is a situation in which the body perceives physical damage or risk of survival, that reaches the cerebral amygdala.
The pathway for the readiness response is the amygdala → hypothalamus → adenohypophysis → adrenal gland, where ACTH arrives and promotes the synthesis of adrenaline and noradrenaline. The response includes increased heart rate and blood pressure, as well as increased muscle strength and endurance, among other physiological effects.
Decreasing pain sensation , heightening the senses or increasing blood supply to the kidneys do not represent direct effects of the fight-and-flight reaction.