Answer:
Answer is B.
Explanation:
<u>Period is duration of time</u>.
Period can be of a second,minute,hour or of Some years.We will give unit according to the duration of time.In the given options second is most obvious because it is used to measure time.
The circulatory system is the transport system for endocrine information. While the nervous system uses neurons, the endocrine chemicals and hormones must circulate through the body via blood vessels. Many glands in your body secrete hormones into the blood.
Cerebrospinal Fluid
Produced by the choroid plexuses of the brain, the cerebral spinal fluid is contained in the subarachnoid cavity and spinal canal. It is reabsorbed by the arachnoid granulations.
Besides acting as a cushion for the CNS, the cerebral spinal fluid plays a critical part in the immunology of the central nervous system, blood flow in the CNS and autoregulation.
the answer is B.extinction can be related to a failure to adapt to changes in the environment.
