The rigth answer is 14.7N
The law of gravitation thus makes it possible to calculate a force exerted between two objects. In a terrestrial reference system, we can then calculate the force exerted between the Earth and an object.
The law applied in this case is P = mass x g (gravitational constant = 9.8 N / kg)
if a book weighs 1.5 kg then: P = 1.5 x 9.8 = 14.7N