Explanation:

When an object is placed at infinity in front of a concave mirror, the rays coming from the object are parallel, and upon reflection, they converge at the mirror’s focal point, forming the image.

- Option 1: The correct outcome is that a real and inverted image is formed at the focal point of the mirror.

- Option 2: A virtual image is not formed by parallel rays in a concave mirror; they're reflected and converge at a real point.

- Option 3: An image formed at infinity by a concave mirror involves an object at the focal point.

- Option 4: Virtual and erect images are typical of convex mirrors or when using a concave mirror in a close-up scenario involving magnification, not at infinity.

Answer: Option 1 - A real and inverted image would be formed at the focal point.