Answer:
Option C: decTotal = decSubtotal + GetSalesTax(decSubtotal)
Step-by-step explanation:
To get sales tax, we need a function can process a subtotal amount and return the tax values. By presuming GetSalesTax() is a function that will return a tax value, this function will expect decSubtotal as the input parameter to the function. Otherwise, there will be no values processed in the function.
The statement decTotal = decSubtotal + GetSalesTax(decSubtotal) will invoke function GetSalesTax() by passing decSubtotal as argument. Next the return value of the function will be added with decSubtotal and the summation amount assigned to the variable decTotal.