1. The minimum value of the function $y=\frac{4 x^{2}+8 x+13}{6(1+x)}(x>0)$ is ( ).
A. 1
B. 2
C. $\frac{25}{12}$
D. $\frac{13}{6}$
1. B.
$y=\frac{4(x+1)^{2}+9}{6(x+1)}=\frac{2(x+1)}{3}+\frac{3}{2(x+1)} \geqslant 2$, when and only when $\frac{2}{3}(x+1)=\frac{3}{2(x+1)}$, i.e., $x=$ $\frac{1}{2}$, the equality holds.