what can you use as a substitute for dumbbells?\na piece of paper\na crayon\na heavy book

what can you use as a substitute for dumbbells?\na piece of paper\na crayon\na heavy book
Answer
Brief Explanations:
Dumbbells are used for strength - training due to their weight. A heavy book has weight and can be gripped like a dumbbell for some basic strength - training exercises, while a piece of paper and a crayon are too light.
Answer:
C. A heavy book