What causes the radio pulses of a pulsar?

a. the star vibrates.
b. as the star spins, beams of radio radiation from it sweep through space. if one of these beams points toward the earth, we observe a pulse.
c. the star undergoes nuclear explosions that generate radio emission.
d. the star's dark orbiting companion periodically eclipses the radio waves emitted by the main star.
e. a black hole near the star absorbs energy from it and re-emits it as radio pulses.

A pulsar (pulsating star)   is a neutron star that emits very intense jets of electromagnetic radiation in the range of radio waves, X-rays or gamma rays, at short and periodic intervals due to its intense magnetic field that induces this emission.

This jet is "observable" on Earth, when the magnetic pole of the star "points" to our planet and then stops pointing a thousandth of a second later due to the fast rotation of the star, appearing again when the same pole returns to point towards Earth.

Then, what is observed in the terrestrial sky are pulses of radiation with a very exact period, which are repeated again and again.