Reference angle is angle C
AT is the opposite side as this leg is not adjacent to angle C (or put another way, point C is nowhere to be found in AT)
AC is the adjacent leg because angle C is part of this segment. It is next to or touching the segment, hence the name "adjacent"
side note: CT is the hypotenuse and always the longest side of the right triangle. It is opposite the largest angle (90 degrees) of this triangle.
