Hey there! I'm happy to help!
We see that this is an isosceles triangle. This means that two sides are the same length. . We can see that the sides DE and EF are marked with two orange lines, which shows that they are congruent.
We want to find the measure of angle D. We see that our two lines of equal length both create an angle with the hypotenuse DF. Since these lines are the exact same length, they are going to have to create the same angle. Even if you just eyeball it, the angles look to be the same.
So, our measure of angle D is going to be the same as angle F. Let's call this measure m and put it into an equation.
2m+92=180 (sum of all angle measures in a triangle is 180)
Subtract 92 from both sides.
2m=88
Divide both sides by 2
m=44
So, the measure of angle D is B. 44°.
Have a wonderful day and keep on learning! :D