Final answer:
The correct conversion factor to convert milliliters to cubic centimeters is 1 mL = 1 cm³, as they are equivalent volumes.
Step-by-step explanation:
To convert the volume of a marble from milliliters to cubic centimeters, the conversion factor you would need is that 1 milliliter (mL) is equal to 1 cubic centimeter (cm³). This is because a milliliter is defined as the volume of a cube that has 1 cm sides, making it identical in volume to a cubic centimeter. The correct conversion factor is therefore 1 mL = 1 cm³, which corresponds to option (a).