Myopia or nearsightedness is caused due to the elongation of eyeball, in myopia a person can see near object clearly but cannot see distant object clearly because in this case the images formed before the retina as we know that the far point of a normal eye is infinity and in myopia the person can only see upto 80m ,hence myopia is the correct answer

Myopia
Myopia, also known as nearsightedness, is a common vision problem where a person is unable to see distant objects clearly. The condition is characterized by the ability to see nearby objects clearly while distant objects appear blurry or out of focus. In the given question, the person is unable to see objects beyond 80 cm, indicating a clear sign of myopia.

Causes of Myopia
Myopia occurs when the eyeball is slightly longer than normal or when the cornea (the clear front surface of the eye) is too curved. These structural abnormalities prevent incoming light from focusing directly on the retina, the light-sensitive tissue at the back of the eye. Instead, the light focuses in front of the retina, causing distant objects to appear blurred.

Diagnosing Myopia
An eye examination by an optometrist or ophthalmologist can diagnose myopia. During the examination, the person is asked to read a chart from a distance, and the doctor assesses their ability to see the letters clearly. If the person has difficulty reading letters that appear farther away, they are likely to be diagnosed with myopia.

Correcting Myopia
Myopia can be corrected with the use of corrective lenses, such as glasses or contact lenses. These lenses help to refocus the incoming light directly onto the retina, allowing the person to see distant objects clearly. The prescription for myopia is indicated by a negative number, which represents the strength of the lens needed to correct the condition.

Complications of Myopia
If left uncorrected, myopia can lead to several complications, including headaches, eye strain, and fatigue. In addition, people with myopia may be at a higher risk of developing other eye conditions, such as retinal detachment, cataracts, and glaucoma.

Conclusion
In summary, myopia is a vision defect where a person is unable to see distant objects clearly. It is caused by structural abnormalities in the eye, resulting in the light focusing in front of the retina. Myopia can be diagnosed through an eye examination and corrected with the use of corrective lenses. If left untreated, myopia can lead to various complications and increase the risk of other eye conditions.