Gillis Corporation sells merchandise on account for $$1,000$ to Mountain Corporation with credit terms of $\frac{2}{10},\frac{n}{30}.$ Mountain returns $$400$ of merchandise that was seriously defective and at the same time includes a cheque to settle the account within the discount period. What entry does Gillis make upon receipt of the cheque?

$($a$)$ Cash

Sales Returns and Allowances

Accounts Receivable

$($b$)$ Cash

Sales Returns and Allowances

Sales Discounts

Accounts Receivable

$600$

$380$

Cash

Sales Returns and Allowances

Sales Discounts

Accounts Receivable

$1,000$

$588$

$600$

$392$

$8$

$980$

$($d$)$ Cash $.$

Sales Discounts

$580$

Sales Returns and Allowances

Accounts Receivable

$1,000$