When a ray of light passes through the first principal focus of a convex lens: 

Explanation:

The point where incident rays passes through a point on the principal axis is called first focus.

• When a ray of light passing through a principal focus, after refraction from a convex lens, will emerge parallel to the principal axis.
• When ray of light crossing through a principal focus, after refraction from a convex lens, will appear parallel to the principal axis. A ray of light developing to match at the principal focus of a concave lens, after refraction, will develop parallel to the principal axis.

• One ray of light becomes parallel to the principal axis of the lens and thus, passes through another focus after refraction through the lens. Another ray of light passes through the optical centre of the lens and goes straight. Therefore, the image formed is: At infinity, Real and inverted, highly enlarged.
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So, the correct answer is Option-1-after refraction it emerges parallel to the principal axis.