"It is twelve a.m. right now."
Use of 12 am / pm, whilst matching the japanese 午前 / 午後 , is best avoided. Zero [hour] (零) or less directly, midnight, work a bit better as are more unambiguous
Just as a heads up, as far as I know, nowhere in the lessons thus far has the character 零 been covered, and it is not a choice to pick from on this question. ゼロ was mentioned during the time lessons, but I suspect this is different from 零.
This needs to be corrected either so that 零 is a choice to pick from, or when you get it wrong, it should instead inform you that れい was the correct choice. I have consistently been missing this question every time I re-work this lesson now because I can never find the correct translation to use from the choices provided. I only figured out what the problem was when I looked at this discussion page.
Came to say this - I am repeatedly corrected to use 零 when the option isn't presented as available (and hasn't been taught).