What does this sign mean?

Witch one is it soo it the the question b. a,b, c,d

Which domain endings indicate websites that are most likely to be reliable sources? check all that apply. sites ending in .net

The declining axolotl population in mexico city is an example of in overcrowded cities. a. the surpassing of support capacity b. changes to natural environments and native species c. the lack of safe homes and tenured spaces d. the effects of a growing urban heat island