next question: What is the difference between one having solidity?
Options:
- openness
- fluidity
- hollowness
- weakness
- instability
reasoning:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Openness is related with solidity. The difference between one having solidity is openness. The answer is openness.