Answer:
1 = A
2 = B
3 = B
Explanation:
1) Black holes occur when really big stars collapse on themselves. And, in order to get big, the star has to be an old one.
2) A black hole is something huge that swallows up everything, while a protostar is just the very beginning of a star.
3) Scientist can't truly know for sure, but they can infer about them due to the effects of the surrounding areas.
Answer:
How Does the Immune System Work?
Innate immunity: Everyone is born with innate (or natural) immunity, a type of general protection. ...
Adaptive immunity: Adaptive (or active) immunity develops throughout our lives. ...
Passive immunity: Passive immunity is "borrowed" from another source and it lasts for a short time.
Answer: Redshift and blueshift describe how light shifts toward shorter or longer wavelengths as objects in space (such as stars or galaxies) move closer or farther away from us. ... When an object moves away from us, the light is shifted to the red end of the spectrum, as its wavelengths get longer.
Explanation:
