When a pencil is placed upright at a distance of 10 cm from a convex lens with a focal length of 15 cm, we can determine the nature of the image formed.

Option 1: Real, inverted and magnified.

This option suggests that the image formed by the convex lens will be real (meaning it can be projected onto a screen), inverted (turned upside down), and magnified (larger than the object). However, this is not consistent with the behavior of a convex lens, so option 1 is incorrect.

Option 2: Real, erect and magnified.

This option suggests that the image formed by the convex lens will be real, erect (not inverted), and magnified. Since the convex lens in question is not capable of producing real, erect images, option 2 is also incorrect.

Option 3: Virtual, erect and reduced.

This option suggests that the image formed by the convex lens will be virtual (cannot be projected onto a screen), erect, and reduced in size compared to the object. However, this is not accurate for a convex lens, so option 3 is also incorrect.

Option 4: Virtual, erect and magnified.

This option suggests that the image formed by the convex lens will be virtual, erect,