(A) First and last
(D) Simple decay
If your business has a short buying cycle, you should use the Simple decay attribution model.
A simple decay attribution model is a multi-touch attribution model that gives some credit to all the channels that led to your customer converting, with that amount of credit being less (decaying) the further back in time the channel was interacted with.
This question is a part of the HubSpot Digital Advertising Certification Exam. You can find answers to all the questions asked in this exam on our HubSpot Digital Advertising Certification Exam Answers page.