Answer:
The indigenous peoples of the Americas arrived in North America via the Bering Strait land bridge, which existed approximately 15,000 years ago between Siberia and Alaska, and probably also via a succession of sea migrations from Asia.
Explanation:
Pulsar is also called as<u> neutron stars or white dwarfs.</u> These are formed after the supernova explosion. Their mass is higher than a normal star. And the most different thing we find in pulsar is that, in a pulsar the proton and electrons combine themselves to form a neutron. That's why this is also called as neutron star. After neutron or white dwarf the star goes to the black dwarf stage.
Remember when the core of the iron becomes iron rich that time it cannot sustain further nucleo synthesis process, that's why it goes for a supernova explosion. Which results the formation of neutron star or white dwarf, followed by black dwarf or black hole.
As you travel from the North Pole toward the equator, you would expect to see tundra; grasslands; tropical rain forest. The correct option among all the options that are given in the question is the first option or option "a". I hope that this is the answer you were looking for and it has come to your help.