Referring to Weekly Pondering $12,$ which statement represents what we mostly discussed?

$(1$ Point$)$

We can infer the properties of dark matter $($a common, massive particle that interacts weakly$)$ by studying the bullet cluster and galactic rotation curves.$$

A popular model of MOND alters Newton's Second Law so that it gives different predictions on galactic scales.$$

Quite a bit of the missing matter in the universe $($dark matter$)$ is just black holes that are hard to detect.

weekly poundering $12$