What types of cells can use solution c as a carbon source, and what types of cells could only use solution g? † there’s an important difference because that c is an inorganic carbon source and g is a "fixed" organic carbon source.

Cells that can use an inorganic carbon source include organisms called phototrophs like some bacteria (cyanobacteria), algae and plants. This type of organism will use solution C.

Cells that can use an organic carbon source include organism called chemoorganotrophs like most bacteria, fungi and animals. This organism will use solution G.

Explanation:

Organisms that use chemicals as an energy source are called chemotrophs. Inside this category we can find three subcategories:

Chemolithotrophs: Are organisms that can use the energy available from inorganic compounds that do not contain carbon (gaseous hydrogen H2, hydrogen sulfide H2S, ammoniaNH4+, etc.).    

Chemooorganotrophs: Are the organisms that use organic chemicals as carbon source for energy intake. (Glucose, acetate, tec.) This type of organism includes most of bacteria, fungi and animals.

Phototrophs: This organism use an inorganic carbon source (CO2) and light to elaborate energy. This type of organism includes phototrophic bacteria like cyanobacteria, algae, and plants.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.