Correct Answer: To validate the sales taxes by creating a sales order and generating a proforma invoice, follow these steps: First, create a sales order by navigating to Navigation pane > Modules > Accounts Receivable > Sales orders > All sales orders. Select 'New' to create a new sales order. In the Customer account field, select the drop-down button to open the lookup and choose the customer record for Contoso Retail Los Angeles. Confirm by selecting 'OK'. Under the Sales order lines section, select the Sales order line. In the Item number field, select the drop-down button to open the lookup and choose item T0001. If the Size dimension is not displayed, click on Sales order line > Display > Dimensions, and select the Size dimension. Confirm by clicking 'OK'. In the Size field, select the drop-down button to open the lookup and choose Size 10. In the Quantity field, enter 1. Navigate to the Sell tab and under Generate, select Confirm sales order, then click 'OK'. Next, create the proforma invoice by clicking on the Invoice tab on the sales order page. Under Generate, select Pro forma invoice, set the Print invoice option to Yes, and confirm by clicking 'OK'. Click on Export to save the invoice in Microsoft Excel format to the Downloads\Sales folder, ensuring all steps validate the sales taxes correctly.