Which type of star would mostly likely turn into a black hole if it pulled in mass from a companion star? a. red giant b. white dwarf c. neutron star d. main sequence star

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The answer is 

B.white dwarf

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Option- C

The type of star would mostly likely turn into a black hole if it pulled in mass from a companion star is the neutron star.                                                        

Explanation:

While, the black holes formation requires an extensive amount of mass been pulled by the respective star or any celestial entity for the formation of a quark star. As the formation of such masses requires an enormous amount of gravitational force that links up these materials into one and forms a much different results like the black holes itself.