Do it yourself I am not typing an essay just for you.
Salamanders can regrow entire limbs and regenerate parts of major organs, an ability that relies on their immune systems, research now shows. ... They then wiped out some or all of the macrophage cells to determine whether these cells were essential for regrowing the limbs.
B is the answer to this question.
1. Not sleeping
2. His brain cant function properly due to him being tired
3. Get some sleep or get a schedule to efficiently practice mathematics
Pls mark as brainliest
