Final answer:
A 10%, 4%, or 13% sugar solution would be considered hypotonic for a piece of carrot with an initial internal sugar concentration of 15%, causing it to gain mass and swell.
Step-by-step explanation:
An hypotonic solution has a lower solute concentration than another solution. In this case, the solution that would be considered hypotonic for the piece of carrot with an initial internal sugar concentration of 15% is the one with a lower sugar concentration.
Based on the given options, the solutions that are hypotonic are: 10% (option b), 4% (option c), and 13% (option e). These solutions will cause the carrot to gain mass and swell as water moves into the carrot cells by osmosis.