Which of the following is true of the formation of coal? A . Hot lava from Earth's surface turns into coal under great pressure.
B. Most coal was formed over 250 million years ago, due to the decomposed remains of the millions of organisms that died during the Great Dying.

Which is an advantage of having memory cells when a pathogen is encountered for a second time. a) the memory cells are what proliferate into clones of cells in response to the binding of an antigen. b) memory cells are vital to the primary immune response in that they immediately recognize pathogens even at the first encounter. c) memory cells are essentially effector cells that are short lived and attack antigens even without having a receptor specific to that antigen. d) it ensures that more lymphocytes with a receptor specific to a particular antigen will be present than in a host that had never encountered that pathogen.