The answer would be A (Endocrine-Nervous)
Hope this helps!
I agree with the speaker that the ability to learn is not fixed and can change with your effort because the more you persevere to know, the more knowledge you will gain and acquire. Moreover, the more we sharpen our brain, it will get more information that we need and we can use it in our way of life especially in our decision-making.
The answer is Mentruation
