Question

1. what is the end result of the death of an extremely high - mass star? brown dwarf nebula black hole pulsar

Explanation:

When an extremely high - mass star runs out of fuel, its core collapses under its own gravity. If the mass of the core is above a certain threshold (the Tolman - Oppenheimer - Volkoff limit), the collapse continues until a black hole is formed. Brown dwarfs are failed stars, nebulae are clouds of gas and dust, and pulsars are highly magnetized, rotating neutron stars which are the result of the collapse of less massive stars compared to extremely high - mass ones.

Answer:

C. black hole