You are developing a new ecommerce website for your company. You want customers to receive a customized email notification when they place an order. You need to configure this email service while minimizing deployment effort. What should you do?

A. Create a Cloud Function that is triggered by a create type event in Firestore, B. Create an email-sending application hosted on Compute Engine that is invoked by an HTTP request. C. Create an email notification channel, and set up an alerting policy that is based on log metrics from a create type event. D. Use Pub/Sub to send an email when the orders/ API returns an HTTP response of 200 OK.