Number of point to point link
The answer depends on your definition of "fully connected network". If the normal meaning is used, where each connection is bidirectional, then the answer is 1225.

It's possible that the questioner is using a weird definition where each link is unidirectional, in which case the answer would be 50*50=2500. This would (I think) be very unusual, and it's more likely that the questioner just made a mistake. If this were ever asked in a formal setting, I would say 1225, and if marked as wrong, I would complain to the examining body.

It's probable that the results you're seeing on the internet have all been copied from the same incorrect source.