The correct answer is B. Hydrogen.
Hydrogen is the chemical element with the symbol "H" and atomic number 1. It's the lightest and most abundant chemical element in the universe.
Here's a quick rundown of the other options:
A. Helium - symbol "He", atomic number 2
C. Oxygen - symbol "O", atomic number 8
D. Nitrogen - symbol "N", atomic number 7
![](https://s2.save4k.ru/pic/kmjSN4fbkrQ/maxresdefault.jpg)