During which season in the northern hemisphere is the earth at its farthest distance from the sun?

a.
spring

b.
winter

c.
autumn

d.
summer

which force holds the planets in their orbits?

a.
electromagnetism

b.
strong nuclear force

c.
weak nuclear force

d.
gravity

what is the name for a star and planets held together by gravity?

a.
solar system

b.
galaxy

c.
black hole

d.
supernova

which contribution did kepler make to our view of the solar system?

a.

he proposed that gravity kept the planets in their orbits.

b.

he proposed the sun-centered model of the solar system.

c.

he proposed the earth-centered model of the solar system.

d.

he showed that planets moved in elliptical orbits.
plz : (

Which of the following statements is correct in hour our immune system responds to a potential pathogen? a. the adapted immune system will call on the innate immune system to destroy the pathogen. b. b cells will start reading the antigen code immediately and call t cells to assist in destroying the pathogen. c. the skin will be the first line of defense, and then the many phagocytes in the bloodstream will attempt to consume the possible pathogen. d. the t-cells in the adapted immune systems are the first to recognize the pathogen vaccines are weakened forms of disease causing microorganisms, which are given to patients to prevent disease. after the vaccine is administered, the immune system responds by creating a(n) to recognize the a. antigen, antibody b. antibody, antigen c. antibody, antibiotic d. antibiotic, antibody