Answer:
according to google
"An action potential is part of the process that occurs during the firing of a neuron. During the action potential, part of the neural membrane opens to allow positively charged ions inside the cell and negatively charged ions out. This process causes a rapid increase in the positive charge of the nerve fiber."
Density is mass per volume 
With data: 
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Hope this helps.
Explanation:
problem Will start so we need to prevent it.
A. your tuition may be paid by your school district if you receive a passing grade in the course.
B. the courses often take one semester to complete.
C. the end-of-year test requires a score of 3 for you to receive college credit.
D. the courses are taught at the college level.
