Which of the following figures will have its altitude outside the triangle?

We know that the altitude of a triangle is the perpendicular drawn from the vertex of the triangle to the opposite side.

A triangle in which one of the interior angles is greater than 90^o is called an obtuse triangle and in an obtuse-angled triangle, two of its altitudes lie outside the triangle.

The altitudes of the given triangle are drawn as follows.

So, from the figure, it is clear that the last triangle has its altitude outside of the triangle, which is an obtuse-angled triangle.