I have this except from my program and would like to change the line showing the error to say red, how would I do that?

switch (choice)
{
case 1:
{
printf("\nThank you for choosing the Del Mar Store");
printf("\nThe price you entered is: $%10.2f<<<<\n", (price));
printf("The Sales tax on that item is: $%10.2f<<<<\n", (DMPrice));
printf("Bringing your Total Sales to: $%10.2f<<<<\n", (DMTotal));
} break;
case 2:
{
printf("\nThank you for choosing the Encinitas Store");
printf("\nThe price you entered is: $%10.2f<<<<\n", (price));
printf("The Sales Tax on that item is: $%10.2f<<<<\n", (ENPrice));
printf("Bringing your Total Sales to: $%10.2f<<<<\n", (ENTotal));
} break;
case 3:
{
printf("\nThank you for choosing the LaJolla Store");
printf("\nThe price you entered is: $%10.2f<<<<\n", (price));
printf("The Sales Tax on that item is: $%10.2f<<<<\n", (LJPrice));
printf("Bringing your Total Sales to: $%10.2f<<<<\n", (LJTotal));
} break;
default:
//Used to let user know they made an invalid Store Choice.
printf("\nI am sorry that is not a valid choice!\n\n"); This is the line I would like to change to "red" so they know that they made a mistake.
}