Answer with explanation:
A triangle is a polygon ,which has three sides in all.
⇒A triangle is said to be Isosceles , if it's two angles or corresponding sides in front of these two angles are equal.
⇒A triangle is said to be Acute Angle Triangle , if all three angles are less than 90 degree.
⇒A Triangle is said to be Right Angled Triangle, if it's one Angle has measure equal to 90 degree.
⇒Scalene triangle is that triangle,whose all sides are unequal.
Coming to the Question:
There are 5 triangles,A,B ,C,D,and ,E .
If you take the side of square ,as 1 unit
⇒ Triangle A=
Two sides are approximately, 4 units. So, it is a Isosceles Triangle and Acute angled triangle.
⇒ Triangle B=
All three sides has distinct length. All interior angles less than 180 degree.Scalene as well as Acute angled triangle.
⇒ Triangle C=
One Angle is right angle.So,it is right Angled triangle.All three sides are unequal,so we can call it Scalene Triangle.
⇒ Triangle D=
One Angle is right angle.So,it is right Angled triangle as well as Scalene Triangle.
⇒ Triangle E=
Angle greater than 90 degree, and all three sides are unequal.Obtuse Angled Triangle as well as Scalene Triangle.
Option D:
There are exactly three Scalene Triangles.