Killz me when I see this

How do we determine if they are made with matter

Which of the following ideas did greek philosopher democritus contribute to the atomic theory? a. each object is made up of one atom, which varies in size from very small to very large. b. matter is composed of only one kind of particle, which can be easily destroyed. c. every element has a specific type of atom, which remains the same size in all forms of matter. d. all matter is composed of small particles, which combine to make larger objects.

Respiration involves the breakdown of sugar. this process results in the production of energy for the cell. i'm order for cells to produce the most energy, what gas should be present?