Answer:
A. change in abiotic factors
Explanation:
Abiotic factors are those factors that have no life, the most important of which can be mentioned: water, temperature, light, pH, soil, humidity, oxygen and nutrients.
The answer is Sir Isaac Newton
The only thing we know about so far that can shift wavelengths of light
to longer wavelengths is when the source of the light is moving away
from the observer.
When we look at the light from distant galaxies, the light from them is
always shifted to longer wavelengths than it SHOULD have.
AND ... The farther away from us a galaxy IS, the MORE its light is
shifted to wavelengths longer than it should have.
So far, this indicates to us that the whole universe is expanding.
That's the only way to understand what we see, because that's
the only thing we know of that can shift light to longer wavelengths.
By the way ... The most interesting thing about these observations
and measurements is: When astronomers see this light from distant
galaxies and measure the wavelengths, how do they know how far
the wavelengths shifted ? How do they know what the wavelengths
SHOULD be ?
I'll leave you to read about that in the next few years.
Using Fnet= ma, constant motion means 0 acceleration, Fnet ( force ) will be also 0
14. Reactants:
Magnesium Chloride: 
, since magnesium (Mg) has 2 valence electrons while chlorine (Cl) has 1 vacancy, so they are in ratio 1:2
Sodium oxide: 
, since sodium (Na) has 1 valence electron while oxygen (O) has 2 vacancies, so they are in ratio 2:1
15. Products:
Magnesium oxide: 
, since magnesium (Mg) has 2 valence electrons and oxygen (O) has 2 vacancies, so they are in ratio 1:1
Sodium chloride: 
, since sodium (Na) has 1 valence electron and chlorine (Cl) has 1 vacancy, so they are in ratio 1:1
16: Balanced reaction:
we see that on the reactant side we have: 1 atom of Mg, 2 atoms of Cl, 2 atoms of Na and 1 atom of O. By putting a 2 in front of NaCl, we have exactly the same on the product side: 1 atom of Mg, 2 atoms of Cl, 2 atoms of Na and 1 atom of O.
17. It is a double-replacement reaction
A double-replacement reaction occurs when two ionic compounds exchange their ions. In this specific case, we see that the Chlorine (initially bond with the magnesium) is then bond with the sodium, while the oxygen (initially bond with the sodium) after the reaction is bond with the magnesium.
