Final answer:
A hypotonic solution for a piece of carrot with a 15% internal sugar concentration would be one with a lower sugar concentration. Options B: 10% and C: 4% are both hypotonic, with C: 4% being the most hypotonic of the available choices.
Step-by-step explanation:
A piece of carrot with an internal sugar concentration of 15% that gains mass and swells when placed into a solution is exposed to a hypotonic solution . This means that the solution has a lower concentration of solute compared to the inside of the carrot. Given the options A: 25%, B: 10%, C: 4%, and D: 70%, the hypotonic solution would be the one with the lower solute concentration than the carrot's internal concentration of 15%. Therefore, the hypotonic solution are B: 10% and C: 4%, with C: 4% being the strongest hypotonic solution relative to the carrot's internal environment.