The most abundant element in universe is: 

Hydrogen being present in the cores of many stars is the most abundant element in the universe. Three-quarters of the mass of the universe is occupied by hydrogen. We should be aware that hydrogen is the element with the highest abundance. It makes up roughly 3/4 of the universe's mass. In the dust clouds between stars, it can be found in enormous amounts. The remaining 25% is largely made up of helium, which comes in second. The third most prevalent element in the universe is oxygen. The most prevalent element on earth, oxygen, makes up around 47% of the planet's mass. Almost everything in the universe is hydrogen. The most abundant element found is hydrogen, which is present in the form of water. Thus hydrogen, the first element in the periodic table is the most abundant element.

Hence, option D is correct.