Final answer:
The characteristic that describes a toy building kit containing plastic solids in a variety of shapes is Volume.
Step-by-step explanation:
The characteristic that describes a toy building kit containing plastic solids in a variety of shapes is Volume. Volume is the amount of space occupied by an object, and in this case, it refers to the size or capacity of the plastic solids in the kit.
For example, if the toy building kit contains plastic cubes, spheres, and cylinders of different sizes and shapes, the volume of each solid will determine its size within the kit.
Therefore, the correct answer to the question is c) Volume.