Could "Explain why you have been late three days in a row!" be correct?
Yes and I have reported it (too).
Explain why you are being late for three days in a row ( WRONG)???
@Shirokage and @Patrick
Both sentences should be correct in my opinion as well. Hope you reported it
Native (NZ) English speaker here.
"are late" incorrect (should not be the model answer)
"are being late" incorrect
"have been late" correct
"were late" correct
Also, the word "for" is optional.