Which is a requirement for natural selection to occur?

Which phrases describe an extrusive rock? check all that apply. fine texture cooled slowly small crystal size found deep underground different, easily observed minerals

The table shows dates and appearance of index fossils. which rock layers can be dated most precisely? a) a layer containing both a fossil 4 and a fossil 3 b) a layer containing both a fossil 2 and a fossil 3 c) a layer containing both a fossil 1 and a fossil 4 d) a layer containing both a fossil 1 and a fossil 2

Patient has just received an organ transplant which treatment would be most effective in preventing the patient’s body from