The correct option is C Both A and B
Let N be Avogadro's number.
The atomic/molar masses of Fe,N2 and H2 are 56 g/mol, 28 g/mol and 2 g/mol respectively.
560 g Fe=560g56g/mol=10 mol Fe=10N atoms.
70 g N2=70g28g/mol=2.5 moles N2=2×2.5N=5N atoms.
Twice of this corresponds to 2×5N=10N.
20 g of H2=20g2g/mol=10 mole H2=2×10N=20N atoms.
Half of this =0.5×20N=10N atoms.
Hence, both A and B are correct options.