Why is מהדובה גדולה just as correct as מהדוב הגדול? I thought they'd both need the ה modifying the word "big".
You're right, they do. מהדובה גדולה is incorrect, it should be מהדובה הגדולה.
Can we get that fixed then please? I also got that and was marked wrong for not selecting it.
Why don't they correct the sentence? Aren't they responsible?
Responsible? Maybe not.
If people want to draw attention to this I suggest posting in their group on Facebook:
Two years later, the missing ה is still missing....
Still not corrected 5/1/19
mi mefachéd me-ha-dov ha-gadól? af echád!
It hasn't been corrected yet!
Still not corrected.
Still not corrected. 11/28/17
Still not corrected 6/29/18
I think I have seen דב instead of דוב. Am I totally wrong?
It is possible you have seen it. דב is also a possible way to write the word, since writing without nikud is flexible.