Henry Poincare argued that in space there are not only rectilinear triangles in which angles equal to two right angles, but also curvilinear triangles in which angles are less than two right angles. He, further, maintained that to name the first on straight is to subscribe to Euclidean geometry and to name the latter straight is tantamount to subscribing to non-Euclidean system.

**Which one of the following accurately represents what is at stake?**

#### Options

Acceptability of Euclidean system

Acceptability of Non-Euclidean system

Confusion in Geometry

Choice of the definition of straight line

#### Solution

**Choice of the definition of straight line**

**Explanation:**

The issue here is the criterion to define a straight line. It 180 degree angle is used as the criterion to decide straight, then Euclidean geometry is followed. But, if less than 180 degree is also considered straight then we are referring to Non-Euclidean geometry. So, the choice of definition of a straight line is the issue at stake. So, 'Choice of the definition of straight line' is correct.