I think the answer is D. ( or supported by observations ). Because theories change over time, they both NEED to be proven, they do NOT go off of consensus, but they do NEED to be supported by observations.
I hope this helps.
Not sure, what youre talking about
Answer:
primary, secondary
Explanation:
primary immunodeficiency diseases are present at birth and usually stem from genetic errors, whereas secondary immunodeficiency diseases are acquired after birth and are due to agents such as infections, irradiation, or steroids
Mountain Bike is the correct answer