What came before the big bang is one of the primary unanswered questions about the origin of

The correct answer for the blank is- Origin of universe.

Big band theory is an explanation about the origin of universe ( that is how universe began or the birth of universe).

Big Bang theory states that all matter ( including past and present time) in the Universe have come into existence at the same time, that is approximately about  13.8 bya ( billion years ago).

At that particular time, all matter was in the form of very small ball ( that is a compact form) with infinite density and excess heat, which is known as a Singularity.

All of a sudden, the singularity started expanding, and the universe that we know today originated.

the reason is because the moon has some form of gravity, and that gravity pulls the ocean tides.

thermal energy is the answer