Final answer:
A plane contains at least two lines because, by definition, a line can be drawn between any two distinct points on a plane, and another line can be drawn starting from a point not on the first line.
Step-by-step explanation:
The conjecture that a plane contains at least two lines can be explained by understanding the properties of a plane in geometry. In geometry, a plane is defined as a flat, two-dimensional surface that extends infinitely in all directions. If we take any two distinct points on a plane, there is exactly one line that connects those two points and lies entirely within the plane. Therefore, starting with two points and drawing a line, we can choose another point not on that line and draw another line. This demonstrates that a plane must contain at least two lines.
Furthermore, we can use the concept of good continuation to support the idea that a plane can have multiple lines. Good continuation is a principle that suggests we are more likely to perceive continuous forms rather than disjointed ones. For example, if two lines appear to overlap, we are more likely to perceive them as a continuation of each other rather than four separate lines intersecting.