Plz help what is the measure of AC ?

D.) 30°

Step-by-step explanation:

I am really hoping you mean angle AC:

If you have a 90° angle in a triangle (like the one created by ACB), the other two angles in the triangle have to add up to 90°. This is because a triangles angles will always add up to 180°. If you already have a 90° angle:

150° is wrong because 150°+90°=240, not a triangle measure

120° is wrong because 120°+90°=210, not a triangle measure

90° is wrong because 90°+90°=180°, but this is only two angles, not three

30° is correct because 30°+90°=120°, less than 180°, leaving room for a third angle.

answer: the dogs need to shift their focus to human scent.

its because the dogs being trained are for search and rescue thus they need to be able to track humans and their specific scent