Answer:Cos C = 5/7 is the correct answer
Step-by-step explanation: In any right angled triangle, such as the one given in this question, the side facing the reference angle is the "opposite"
This means, depending on what you are asked to calculate, either the sine or the cosine of the angle, you usually have two opposites.
Therefore if Sin D = opposite/hypotenuse,
Then Sin D = 5/7
This means the opposite side is 5, while the hypotenuse is 7.
Also note that, the side that extends between the right angle and the reference angle is the "adjacent"
Since we are not given the third side of the triangle, the side that measures 5 would be the adjacent of angle C. (Please refer to the attached diagram).
Therefore angle C already has an adjacent and an hypotenuse. This means we can calculate Cos C = adjacent/hypotenuse
Cos C = 5/7
