1. If 15 | xaxax , then the sum of all five-digit numbers $\overline{x a x a x}$ that satisfy the requirement is ( ).
(A) 50505
(B) 59595
(C) 110100
(D) 220200
- 1. D.

Notice that, $15 \left\lvert\, \overline{x a x a x} \Leftrightarrow\left\{\begin{array}{l}5 \mid \overline{1 \overline{x a x a x}}, \\ 3 \mid \overline{\text { xaxax }} .\end{array}\right.\right.$
From $5 \mid \overline{\text { xaxax }} \Rightarrow x=5$;
From $3 \mid \overline{\text { xaxax }} \Rightarrow 3 \mid (x+a+x+a+x)$
$\Rightarrow 3 \mid 2 a \Rightarrow 3 \mid a \Rightarrow a=0,3,6,9$.
Thus, the five-digit numbers that meet the requirements are
$$
50505,53535,56565,59595 \text {, }
$$

Their sum is 220200.