input: OPTIONS:
- surface
- Skin
- outer
- layer Now, answer this question: Q: The thick skin, found only on the palms of the hands and the soles of the feet, has an extra what? A:
A:
output: layer

input: OPTIONS:
- momentum
- tension
- vibration
- friction Now, answer this question: Q: What force causes waves to topple over and break on the shore? A:
A:
output: friction

input: OPTIONS:
- cellulose
- chromatin
- amino acids
- keratin Now, answer this question: Q: What fills the epidermal cells that make up fingernails and toenails? A:
A:
output:
keratin