See I was actually pretty confused as to why our inputs were 1, 2, 4 and 8. Should I just inform the grader in the beginning and say that let A = 1, B = 2, C = 4, and D = 8? (And then circle the grouping like you said which ill do in a moment). Im honestly just concerned whether the K-map was done correctly right now.Not too happy about their table. They show rows in which all of the inputs are don't cares. That makes zero sense. Then, in those rows, they show the outputs all being LO but add a not telling you to treat them as don't cares. Sloppy.
The inputs should properly encode the values in the left column and then all of the output columns in those rows should have 'x' in them.
But, the intent is pretty obvious.
Then YOU get sloppy.
Your inputs in the table are 1, 2, 4, and 8, but then your K-map uses A, B, C, and D with no indication of how they relate. If I'm a grader, I'm not going to waste my time trying to figure it out. Your function uses four unknown inputs and you don't use any of the four given inputs. Therefore it can't work and gets a zero.
Clean this up and try again.
Also, circle your groupings, because it looks like you are missing some real opportunities to minimize things here.