Answer:
c. natural force or pull toward the earth
Explanation:
Gravity of the earth is the force of attraction that it naturally possesses to attract any mass.
An apple falls on the earth due to this force of gravity.
The force of gravity near to the surface of the earth is given as:
where:
m= mass of the body
g= acceleration due to gravity
The variation of the gravitational force with height is given as:

where:

where
R = radius of the earth 
Explanation:
Given:
v₀ = 0 m/s
a = 9.8 m/s²
t = 4.7 s
Find: Δy
Δy = v₀ t + ½ at²
Δy = (0 m/s) (4.7 s) + ½ (9.8 m/s²) (4.7 s)²
Δy ≈ 110 m
I believe your answer should be C. Speed.
Although scientists can't detect or observe black holes with telescopes that detect x-rays, light, or other many other different forms of electromagnetic radiation and waves. But they can detect and study them by the effect of matter near it. If a black hole passes through a cloud of interstellar matter, it will draw matter inward (this process is known as accretion). A similar process occurs when a star passes through a black hole. When this happens, a star can break apart as it pulls it self toward it. As the attracted matter accelerates and starts heating up, it emits x-rays that are radiate into space.
Recent studies do show that black do have a very big influence towards neighborhoods around it. The black hole emits gamma ray bursts, devouring nearby stars, and spurring the growth of new stars in some areas while stalling it in others.
Info: https://science.nasa.gov/astrophysics/focus-areas/black-holes
Hope this Helps! (: