Based on the passage, how is a neurotransmitter different from an action potential? A Neurotransmitters do not carry neural messages, but an action potential does. B Neurotransmitters are chemical, and an action potential is electric. C Neurotransmitters carry signals inside the neuron, and an action potential carries signals between neurons. D Neurotransmitters are "all-or-none," but an action potential can fire halfway.

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.