An Isosceles Right Triangle is a right triangle that consist of two equal length legs.
Thus, in an isosceles right triangle, two legs and two acute angles are congruent.
Since it is a right triangle, the angle between the two legs would be 90 degrees, and the legs would be perpendicular to each other.
with these said above, the diagram is a Right Isosceles Triamgle.
therefore, option B is the correct answer.