Whats do you want to know?
It should be D, cells are parts, tissue is part and organ is part of a system.
Answer:
the molar mass of any element can be determined by finding the atomic mass of the element on the periodic table for example, if the atomic mass of sulfer is 32.066 amu, then it's molar mass is 32.066 g / mol
It is important to take note of th temperature in determining the density of a substance because this will set as a basis and will likely be a variable in the experiment because this will also contribute on the effects of the experiment and a basis of how the experiment has turned to be that way.