D. Things that are kept constant.
Controls are used in an experiment where some variable is being changed. By only changing one thing and keeping the others constant they can make sure that any change in the results is caused by the variable and not the constant, since the constant didn’t change.
The agent that kills bacteria is called bactericidal. Bactericidal agents act directly by destroying the present bacteria. It is also different from bacteriostatic, because bacteriostatic means the inhibition of the spread and growth of bacteria only.
Nucleus? is that the type of answer you're looking for?<span />