A watch maker’s glass is a

The lens the watchmaker uses to aid with the mechanical assembly of a watch is known as watch-glass. maker's You should be aware that there is very little space between a watchmaker's vision and his creation.
There are a few things that make it simple to comprehend how watchmaker's glass works and what it is used for.
We'll start by defining a convex lens and discussing its applications.
For people who struggle to recognise items in their immediate environment, convex lenses are utilised in spectacles. For instance, reading issues. In most cases, it occurs because the human eye's lens and retina are no longer separated by as much space. The focus point thus sits beneath the retina.

Convex lenses in glasses cause more refraction, which shortens the focus length. This aids the wearer of glasses in forming a picture at the retina, enabling clearer vision of things that are closer to them. The watchmaker may benefit from the same idea because when he employs a convex lens, the pictures he sees appear larger than they actually are. It makes it easier for him to make out the watch's tiny gears. The watchmaker can see enlarged pictures using convex lenses. Additionally, he has the option of selecting a convex lens with the necessary magnification. Thus, the convex lens aids the watchmaker in having a good view of the microscopic components of a watch. This enables him to manufacture and repair the minute components that make up a watch.

Hence, the correct answer is option A.