Correct option is A
A
thumb screw is a type of screw that has a
circular-shaped head with ridges or knurls, designed to be tightened or loosened by hand without the use of tools. The circular head is ergonomically designed to allow for an easy grip with fingers, making it suitable for applications where frequent adjustments are needed.
Thumb screws are commonly used in light-duty applications, such as securing panels, fixing covers, or assembling furniture.
Hexagonal heads are typically found in
hex bolts or
hex screws, which require a wrench or socket for tightening. They are not used in thumb screws, as these are meant to be operated by hand.
