Question

question 4
dark matter is thought to exist because
it explains why the expansion of the universe is accelerating.
it is the dark side of the force.
scientists have found enough rogue planets & brown dwarfs to explain all the invisible matter.
we can observe its gravitational influence on visible matter via gravitational lensing, etc.
the milky way is a barred spiral galaxy.
starburst galaxies are observed throughout the universe.

Explanation:

Dark matter is undetected directly but its existence is inferred from its gravitational effects on visible matter, like gravitational lensing. The acceleration of the universe's expansion is attributed to dark energy. The "Dark Side of the Force" is from a fictional universe. Rogue planets and brown dwarfs do not account for all invisible matter. The shape of the Milky - Way and the presence of starburst galaxies are not related to the existence of dark matter.

Answer:

we can observe its gravitational influence on visible matter via gravitational lensing, etc.