Action potentials at a chemical synapse
a. travel from presynaptic terminal to postsynaptic membrane.
b. travel from postsynaptic membrane to presynaptic terminal.
c. travel back and forth from presynaptic terminal to postsynaptic
membrane.
d. travel from presynaptic terminal to presynaptic membrane.
e. stop at the presynaptic terminal and are regenerated on the
postsynaptic membrane.

Option-A

Explanation:

The impulse generated in the neuron is transmitted in the form of an electrical signal or action potential which gets converted into a chemical synapse to transmit the signal from one synapse to another synapse.

The junction at which the electrical signal is converted into the chemical signal is called a synapse. The neurons which produce the chemicals called neurotransmitter from the axon terminal is called the presynaptic neuron and the neuron which receives the signal through receptors of the dendrites is known as the postsynaptic neuron.  

Thus, Option-A is the correct answer.

because they were born with essential oils in their veins

Corona Virus originated in Wu Han China and quickly spread across the world through trade routes

Explanation:

The global response to the Corona Virus was to shutdown, Lockdown, mantain hygiene and Social distancing