Answer: the correct answer is (B) He did not know that interstellar dust made it hard from him to see a large part of the Milky Way's disk.
Explanation:
We live in a dusty Galaxy. Because interstellar dust absorbs the light from stars, Herschel could see only those stars within about 6000 light-years of the Sun.
This sequence refer to how neurons send messages electrochemically. When the neurons are at rest, they are at its resting potential at -70 millivolts. If the neurons in the brain send messages, a spike would occur until it reaches the threshold potential at -55 mV. If it reaches the threshold potential, then an action potential occurs.Hence, the sequence would be letter C.
