D photosynthesis is the function of a chloroplast
I just took a test on this subject and the correct answer is D Tetrad.
Conjugation. hope this helps you out!
This would be a D) "physical model."
It's not natural, because it's not out in nature.
It's not conceptual because that would just be ideas, arbitrary compared to physical ones.
And it's not mathematical, because that would only involve equations, graphs, and tables.