Because, substances can pass through it while others can not but Oxygen, good molecules,
and waste products can only go through it.
Answer:
Because having 3 eyes or 6 does isnt harmful but having 3 arms or legs you could get seriously hurt or lose the limb and bleed out.
Explanation:
Toward or at the front of the body or a structure in front of another structure.
The answer is Ventral.
Hope this helps.
The answer is chemical energy
