During your oral report, you should speak at a medium pace because— it will help your audience understand you
it will make your speech longer
it will help you remember what to say

it will help your audience understand you ...

there is saying "first impression is the last impression"... so if they understand you then understanding between you and audience is very high .. so if you describe in short also then they can understand easily

what excerpt?

explanation:

it would be d because the however is more proper and the comma is placed in the right spot