D. It Is The Most Fitting Answer. The Other 3 Equal More Than Needed.
EF is tangent to the circle we'll assume; otherwise there's no progress.
Call the center C. ECD is isosceles, formed from two radii and the chord.
Angle CED is complementary to DEF
CED = 90 - 65 = 25 degrees
CDE is congruent, isosceles triangle and all that: CDE=25
That leaves DCE=180-25-25=130 degrees
That's the measure of arc DE as well:
Answer: 130 degrees, choice A
(A) Product of 
and 
is:
(B) Yes.
Product of and = Product of and because multiplication is commutative.
Commutative Property of multiplication says that a.b = b.a.
Thus, multiplication is same irrespective of the order of two numbers.
Composition means that you can plug g(x) into f (x). This is written as "( f o g)(x)", which is pronounced as "f-compose-g of x". And "( f o g)(x)" means " f (g(x))". That is, you plug something in for x, then you plug that value into g, simplify, and then plug the result into f. hope this helps.
This is how you would solve the question.
