Final answer:
The correct answer is three-fourths.
Step-by-step explanation:
The correct answer is c) three-fourths. Each layer should fill approximately three-fourths of the volume of the mold. This means that three-fourths of the volume of the mold should be filled with each layer of the material being used.
which states that a test tube should be about one third full when adding a mixture into it, one might infer that for the student's question each layer should fill approximately one-third the volume of the mold as well.