Which energy resources are increasing their use the most worldwide and where

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.

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

In the sentence "a mining company will consider the distribution of coal when deciding how to mine the coal," what does the word distribution mean?