If X∼Gamma(α,β)X \sim \text{Gamma}(\alpha, \beta)X∼Gamma(α,β), what is the mode of XXX for α>1\alpha > 1α>1?
α−1β\frac{\alpha-1}{\beta}βα−1
αβ\frac{\alpha}{\beta}βα
α+1β\frac{\alpha+1}{\beta}βα+1
βα−1\frac{\beta}{\alpha-1}α−1β