The model shows how pimples are formed in the skin. why do you think this process can occasionally lead to pain? a) the swollen pimple completely stops blood flow to the area, starving the nerves. b) the bacteria replication leads to swelling, which irritates nerves in the dermis. c) the nerves around the pore cannot transmit an action potential, so they can’t send signals. d) the pimple presses on the epidermis, which is where all the sensory receptors in the skin are located.

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.