As a General Rule, You, as a Salesperson, After Receiving

As a general rule, you, as a salesperson, after receiving an order should leave the customer's office as soon as possible to avoid talking yourself out of the order. According to the text, it is not necessary for you to follow this rule if:

A) you explain how to use the product correctly for safety reasons.
B) you are asking the customer for the names of other prospects.
C) you explain how to use the product correctly to make certain the buyer gets full benefit from the purchase.
D) the prospect buys before you expected.
E) the product is technologically complex.