Answer:
The reason our blood is read is because we have iron in our blood. (Also our blood cells are red)
I think your answer is D. Red blood cells
Explanation:
Most animals do have iron in their blood so their blood is red.
But... Octopuses (yes that is the write way to say it) have copper in their blood so their blood is actually blue.
The more you know...
Hope this helped! :)
Brainliest?
