Final answer:
The correct answer is option c. Water (H2O) has the highest concentration in cells due to its vital role in cellular processes. If glucose concentrations are equal inside and outside a cell, there is no net glucose flow due to lack of a concentration gradient, barring active transport or facilitated diffusion.
Step-by-step explanation:
In a typical cell, the compound with the highest concentration is H2O, or water. Water is essential for numerous cellular processes including serving as a solvent for biochemical reactions, maintaining cell structure, and aiding in temperature regulation and nutrient transport. When comparing the concentration of substances like NH3 (ammonia), CO2 (carbon dioxide), CH4 (methane), and glucose, water far exceeds these other compounds in terms of presence within the cell.
If the concentration of glucose was equal inside and outside of the cell, there would generally not be a net flow of glucose across the cell membrane in one direction or the other due to the absence of a concentration gradient. However, active transport mechanisms or facilitated diffusion via carrier proteins could still move glucose against a concentration gradient, depending on the cell's requirements.