Oxygenated blood reaches the fetus through the

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.

1) a

2)c

3)a

4)c

5)b

hope this , if so, your appreciation would be signified through giving   me brainliest, and a you : ) have any further questions? feel   free to ask me in the questions box.