Describe the effect of increased carbon dioxide concentration on blood pH

As it combines with water, it forms carbonic acid, making the blood acidic. So CO2 in the bloodstream lowers the blood pH. When CO2 levels become excessive, a condition known as acidosis occurs. This is defined as the pH of the blood becoming less than 7.35

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.