Oxbow lakes form when:
rivers empty into oceans.
two or more streams empty into a river.
when a bend in a river gets cut off from the main river.
sediments are deposited at the end of a river.

cell division is not regulated in tumor cells.

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.

colors do exist. the color of the sky is actually violet; humans percieve the color of the sky as blue.