Which is quantised in Bohr's atomic model?

angular momentum of the electron

The correct answer is Option (4) → angular momentum of the electron

In Bohr's Atomic Model, the Angular momentum of the electron is quantized. Specially, Bohr postulated the angular momentum (L) of an electron orbiting a nucleus can only take discrete values.

$L=nh=n\frac{h}{2\pi}$  [n = 1,2,3,...]

where,

n = Principle Quantum number

h = Planck's constant