1. The imaginary part of the complex number $z=(1+\mathrm{i})^{2}(2+\mathrm{i})$ is ( ).
(A) -2 i
(B) -2
(C) 4 i
(D) 4
\begin{array}{l}\text {-.1. D. } \\ z=(1+\mathrm{i})^{2}(2+\mathrm{i})=2 \mathrm{i}(2+\mathrm{i})=4 \mathrm{i}-2 \text {. }\end{array}