How many can you check? I personally think its all 4 but i could be wrong :)
Answer:
An electron will only react with a proton in the nucleus via electron capture if there are too many protons in the nucleus. ... But most atoms do not have too many protons, so there is nothing for the electron to interact with. As a result, each electron in a stable atom remains in its spread-out wavefunction shape.
Enzymes - particularly proteases. These break down protein in the stomach in the presence of low pH (acidic material eg stomach acid).
In addition to this, there are many bad bacteria that cause illnesses such as E. Coli or <span>Helicobacter Pylori </span>