I just answered this an the correct answer is B the study of people and their environments <span />
Answer:
b. flat rotation curves in spiral galaxies
Explanation:
Dark matter accounts for majority of the matter in the universe (about 85%). It is considered to be composed of subatomic particles which are yet to be discovered. Dark matter cannot be observed because it does not emit light that can be detected. Only its gravitational effect is visible.
Astronomers when calculated the mass of the visible matter and tried to account for the observed speed of stars in the galaxy, there was a mismatch. To understand what caused this mismatch, astronomers gave name to the invisible matter as the Dark Matter.
The expected velocity of stars should decrease away from the near the center of the galaxy but a constant velocity of stars was observed that is a relatively flat rotation curve was obtained.
Thus, flat rotation curves in spiral galaxies in an evidence of Dark Matter.
A tectonic hazard would be something that isn't expected but only lasts so long.
Example: an earthquake or tsunami
The best example is an earthquake
Immediate responses would be to take shelter under a sturdy building or get to high grounds where nothing can fall on you.
The number of deaths could be reduced by having regular safety checks of buildings and if you know you are near tectonic plate shifting then the building should be built with study material.
I might be wrong but I think the answer is
Continental deflection
