Respuesta :
The correct answer is option A, that is, the vinegar solution was hypotonic, causing the egg to gain mass.
A hypotonic solution refers to any kind of solution, which exhibits a lower osmotic pressure than another solution. In biology terms, this usually means a solution that exhibits less solute and more water in comparison to another solution.
In the given case, the egg is placed in vinegar (a hypotonic solution), thus water will get inside the egg making the egg to gain mass.