Counting tree rings is an example of which type of dating?

Environmental impacts on evolution : mastery test

Elephants in the savanna regions of africa dig holes in dried up river beds to reach water lying just below the surface. these holes provide drinking water for other animals as well. so, without the elephants, many animals might otherwise die from lack of water during the dry season. the location in which the elephants live is an example of a/n and the role they play in creating water holes is an example of a a) ecosystem; habitat b) community; niche c) habitat; niche d) niche; habitat

What is a sex-linked genetic disorder that disrupts the blood's ability to clot? a.achondroplasia b.huntington's disease c.hemophilia d.albinism