Which of the following best describes what would happen if a 1.5-solar-mass neutron star, with a diameter of a few kilometers, were suddenly to appear in your home town?

The scenario described involves the sudden appearance of a 1.5-solar-mass neutron star in a local area. Neutron stars are incredibly dense remnants of supernovae, and they possess an immense gravitational pull due to their mass concentrated within a very small radius, typically just a few kilometers.

If a neutron star were to suddenly materialize in your hometown, its gravitational influence would be overwhelmingly powerful. The compression of the gravitational field from the neutron star would draw in the Earth's mass, leading to extreme gravitational effects. Given that a neutron star's density is about 400 million times that of water, the mass of Earth would ultimately be pulled towards the neutron star.

In this context, the choice indicating that the entire Earth would end up as a thin layer over the surface of the neutron star accurately reflects the physical consequences of such an event. This suggests that Earth’s matter would be stripped away and compressed into a thin layer due to the intense gravitational forces exerted by the neutron star, thereby providing a realistic depiction of the catastrophic outcome of such an appearance.

The other options, while they propose extreme scenarios or downplay the effects of the neutron star, do not align with the understanding of gravitational physics and stellar remnants.