Final answer:
The constraint that should be used on sale dates in queries to calculate the cost of goods sold is BETWEEN [begin_date] and [balance_date].
Step-by-step explanation:
When calculating the cost of goods sold in queries, the constraint that should be used on the sale dates is 2) BETWEEN [begin_date] and [balance_date]. This constraint ensures that only the sales that occurred between the specified begin date and the balance date are considered in the calculation.
For example, if the begin date is January 1st and the balance date is December 31st, the constraint would return the sales that happened throughout the entire year. This provides an accurate calculation of the cost of goods sold for that year.