Multiple choice

Why is blood red?

  1. Red bloods cells were dyed red in the body.

  2. The blood plasma is originally red

  3. Blood is red due to the presence of oxygen in the cell

  4. Blood is red due to the presence of hemoglobin

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Blood is red because of hemoglobin, an iron-rich protein in red blood cells that binds to oxygen and reflects red light.