Standard sea level feed pressure in millibars is

To express air pressure, he used the bar, which is a metric unit of pressure; one bar is slightly less than the Standard Atmospheric Pressure at sea level, which is defined as 1.01325 bar or about 14.7 pounds per square inch. The millibar (mbar) is equal to one-thousandth of a bar, or 1,000 dynes per square centimeter.

hope this helps :) sorry if it doesn't

b is the best answer for this question.

satellites are frequently used to make observations of the orbit on earth