What’s number 4 and 5?

i think that you are smart and you should fit for it out

brain development. a child's brain undergoes an amazing period of development from birth to three—producing more than a million neural connections each second. the development of the brain is influenced by many factors, including a child's relationships, experiences and environment.

explanation:

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.

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added