Some doctors recommend at least 30 minutes of physical activity each day.

a logos

b ethos

c pathos

d bias

Logos: appeal to logic (uses facts, statistics, and reasoning). An example is: there was more than ten research studies conducted in 2017, which came to a conclusion of the ineffectiveness of the medicine.

Ethos: appeal to credibility. An example is: a doctor saying, "I recommend this medicine! It's very effective."

Pathos: appeal to emotions. An example is: "buy this medicine now! If you die, your loved ones will be sad."

The sentence is an example of ethos. The doctors are the credible source.