On July 31, Tractor Supplies sold merchandise to J. Robson on account. The sales price was $8,400, and the cost of goods sold was $6,300. The sales revenue was recorded immediately, but the entry recording the cost of goods sold was dated August 2. As a result, net income for July was

overstated by $2,100.
overstated by $6,300.
not affected, but the net income for August is understated.
overstated by $8,400.