I want help OCR A-level Nuclear and particle physics question

here the are following questions

The answer is D, but I do not know how. can u explain ?

quantum physics - why is it B? 2. Electrons travelling through a thin layer of polycrystalline metal are diffracted. electrons i metal diffraction rings Which statement is correct about these electrons? The electrons travel as photons through the metal. The electrons have a wavelength of about 107 m. The electrons are diffracted by holes in the metal. The electrons repel each other to produce the diffraction. oOowmx> A graph of binding energy per nucleon against nucleon number is shown below. binding energy per nucleon nucleon number Which nucleus, A, B, C, or D, shown on the graph has the largest magnitude of binding energy