Answer:
C. logos
Step-by-step explanation:
The rhetorical appeal he uses is logos.
Logos is known to be a rhetorical appeal which uses logic and reason to convince or persuade an audience. It uses facts, charts, statistics, data and graphs to give its reasons.
So, logos simply means to reason with your audience through providing facts and data or giving them historical analogy.
President Biden referring to "five years" when "he was a sitting Vice president of the United States" actually gives facts in order to convince his audience.
Option C is the correct answer.