"Ini hari pertama bulan Maret."

Translation: This is the first day of March.

[SilentShuffle]

"Today is the first of March" is more natural English and should be an accepted solution.

[KyrieDomineJesus]

Hm, Duo has a very strict policy about "'ini' at the start of a sentence"... It is the subject of the sentence and they insist it has to be translated with "This is ..."

When I started out with Duo I was annoyed at the often clunky (and sometimes outright false) English... but I'm beginning to see why they do it... and, I have to admit, I'm beginning to appreciate it. When you start to learn a language, you should at first translate (i.e. prove you understand the meaning), and only once you have a really firm grasp on the grammar you can start to interpret (i.e. turn it into fluent English that retains the full sense of the meaning).

If you skip step one and you reach more complex sentences later on, it will come back to bite you...

[KyrieDomineJesus]

(Also: the sentence does actually not specify they are talking about today. Someone might be pointing at a flyer "Rock-concert next friday" and say "this is the first day of march!")