We have integrated Outlook with Dynamics sales,
When you receive an email from a customer, our user want to track this against the opportunity, but is not able to do this,
In the example below I tested the scenario, an account has been created, the contact linked to the account and the opportunity is also created, Therefore, I could choose one of the three options..

In case of my user, the account, contact and opportunity are created in dynamics and eventually the mail is tracked on the account and contact and is visible in the time line, but not to the opportunity.
He does not get the option to track the mails against the opportunity.
As far as I can see the email set-up and system requirements related to Outlook and Dynamics are correct.
What would be the reason?