Scientists have recently found evidence that black holes—regions of space in which matter is so concentrated and the pull of gravity so powerful that nothing, not even light, can emerge from them—probably exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.


(A) exist at the core of nearly all galaxies and the mass of each black hole is proportional to

Mass of each balck hole is proportional to its host galaxy- Incorrect comparison. Eliminate.


Mass of each balck hole is proportional to the mass of its host galaxy or

Mass of each balck hole is proportional to that of its host galaxy


(B) exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of

The use of “that of” corrects the comparison error present in Option A. 

Scientists have found evidence 

  1. That blockholes exist at the..

  2. And that the mass of each black hole is proportional to that of its host galaxy. Correct


(C) exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to


Same as A. Eliminate


(D) exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of

The singular verb “exists” doesn’t agree with the plural subject “black holes”. Eliminate


(E) exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of

Same as D. Eliminate