Neo Smith, investment advisor, decides to change the recommendation from "Buy" to "Sell" for the company Montes Verdes, SA$.$ He sends the communication to all his clients electronically on Wednesday. The next day, a client calls to place an order to buy $100$ lots of Montes Verdes stock. In this circumstance, the best course of action by Smith is:

a$.$ Accept the purchase order.

b$.$ Explain the change in recommendation to the customer before accepting the order.

c$.$ Do not accept the order, because it is contrary to the recommendation.