What is the correct order (starting from the surface) of earth’s layers?
a. crust, outer core, inner core, mantle
b. mantle, outer core, inner core, crust
c. crust, mantle, outer core, inner core
d. outer core, inner core, crust, mantle

/the trachea, commonly known as the windpipe

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.