The presence of is the key difference between gray and white matter.

Some birds look for food near cattle and other livestock. the movement of the cattle churns up the ground, making insects available to the birds. the cattle appear to be unaffected by the presence of the birds. what kind of relationship exists between the birds and the cattle? o a. parasitism o b. commensalism o c. predation o d. mutualism

Plz ! ive been stuck on this forever

Which of the following is a period in the paleozoic era? devonian cambrian permian all of the above