I Think The answer is b I hope it helps
Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The sympathetic nervous system (SNS) releases the hormones (catecholamines - epinephrine and norepinephrine) to accelerate the heart rate. The parasympathetic nervous system (PNS) releases the hormone acetylcholine to slow the heart rate. Such factors as stress, caffeine, and excitement may temporarily accelerate your heart rate, while meditating or taking slow, deep breaths may help to slow your heart rate.
All of the above- 1, 2, and 3 These introduce variation into the chromosome or into the zygote and create cells and offspring unique from the parents.
Meninges and cerebrospinal fluid both protect the brain from physical shock.
Meninges is one of the membranes that engulf the brain .
Cerebrospinal fluid is the fluid that the brain floats in and absorbs shocks. #answerwithquality #BAL
The answer is elevation :)
