To determine the number of shirts Natalie can buy without exceeding her budget of $65, we can set up the inequality where the cost of the dress and shirts is less than or equal to $65.
She spends $26 on the dress and each shirt costs $13. Let \( x \) be the number of shirts. The total cost can be expressed as:
\[ 26 + 13x \]
We want this total to be less than or equal to $65:
\[ 26 + 13x \leq 65 \]
So the correct inequality is:
\[ \mathbf{26 + 13x \leq 65} \]