The correct option is C i - respiration,
ii - respiratory substrates
The breakdown of C-C bonds of compounds via oxidation in the cells to obtain energy is called respiration. The compounds that are used for this oxidation are called respiratory substrates.
Breathing is an act of movement of gases between the external environment and a specialised organ such as gills, lungs, etc.
Oxidising agents are the agents that help in the loss of electrons or hydrogen atoms or addition of oxygen to any molecule.
Reduction is the process in which there is a gain of electrons or the addition of hydrogen atom or loss of oxygen atom from a molecule.
Reducing agents are the agents that help in gain of electrons or the addition of hydrogen atom or loss of oxygen from any molecule.
Photosynthesis is the process of the formation of complex organic compounds with the help of sunlight and chlorophyll. Photosynthesis requires molecules such as carbon dioxide and water that can be termed as photosynthetic substrates.