The discrete uniform distribution is on the interval 8 ≤ x ≤ 10. Therefore the probability density function (shown in the figure) is P(x) = 1/3 = 1/3 for x = 8, 9, 10 = 0 otherwse
The mean is μ = 1/3.
The variance is σ² = Σp(x) (x- μ)²
Because x - μ = 0 for x = 8,9,10, therefore σ² = 0
I believe it’s A — atoms in solids are closest together, atoms in liquids are close, but not as compact as in solids, and atoms in gasses aren’t close are all, and they’re constantly moving.