把 $x \to 0^{+}$ 时的无穷小量 $\alpha = \int_{0}^{x} \cos(t^{2}) \, \mathrm{d}t$ , $\beta = \int_{0}^{x^{2}} \tan \sqrt{t} \, \mathrm{d}t$ , $\gamma = \int_{0}^{\sqrt{x}} \sin (t^{3}) \, \mathrm{d}t$ 排列起来, 使排在后面的是前一个的高阶无穷小量, 则正确的排列次序是( ) (A) $\alpha, \beta, \gamma$ . (B) $\alpha, \gamma, \beta$ . (C) $\beta, \alpha, \gamma$ . (D) $\beta, \gamma, \alpha$ .