Explanation

The number of moles is mass divided by molar mass. Helium is monatomic with a molar mass of approximately 4 g/mol (atomic mass ~4). So 104 g of helium gives 104/4 = 26 moles. The distractors come from using a wrong molar mass: 2 g/mol would give 52, 8 g/mol would give 13. Hence option (B) 26.