4. Given $a \geqslant b \geqslant c>0, a+b+c \leqslant 4$. Then the maximum value of $a^{2}+3 b^{2}+5 c^{2}$ is ( ).
(A) 18
(B) 16
(C) 14
(D) 12
4. B.

Notice,
$$
\begin{array}{l}
16=4^{2} \geqslant(a+b+c)^{2} \\
=a^{2}+b^{2}+c^{2}+2 a b+2 a c+2 b c \\
\geqslant a^{2}+b^{2}+c^{2}+2 b^{2}+2 c^{2}+2 c^{2} \\
=a^{2}+3 b^{2}+5 c^{2},
\end{array}
$$

i.e., $a^{2}+3 b^{2}+5 c^{2} \leqslant 16$.
The equality holds if and only if $a=b=c=\frac{4}{3}$. Therefore, the maximum value of $a^{2}+3 b^{2}+5 c^{2}$ is 16.