The molar mass is the sum of the mass of all the atoms of a particular molecule.
The unit  of molar mass is grams per mole.
The atomic mass of H = 1.00
The atomic mass of N = 14.00
The molar mass of ammonia = atomic mass of N + 3 x (atomic mass of H)
                        = 14.00 + 3 x (1.00) = 17.00
Therefore the molar mass of ammonia is 17g/mol
The correct answer is  17g/mol.