Planetary orbits about the Sun have slower orbital speed far from the Sun. The rotation curve of our galaxy suggests that orbital speed is constant along the spiral arms. To understand the role of gravity, it has been proposed that our galaxy has mass at great distance from the galaxy center. What does the text identify makes up most of that mass?

A) dark energy
B) stars, protons, neutrons, electrons
C) dark matter
D) none of these

the answer would be a

your answer is c! hope this : )

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force