Which of the following is a very sharp surgical knife?

A scalpel is a very sharp surgical knife specifically designed for precision cutting during surgical procedures. It typically features a straight or curved blade that is extremely sharp and allows for clean incisions into tissues. The design of a scalpel enables surgeons to perform delicate tasks, such as making incisions in skin or muscle with minimal trauma to surrounding areas, which is crucial for effective healing and recovery.

In contrast, scissors are tools used for cutting but do not have the same precision or sharpness as a scalpel. Forceps are gripping and manipulating instruments but do not cut. A drench gun is a device used to deliver liquids, often used in animal husbandry, but it has no cutting capability. Therefore, the unique characteristics of a scalpel make it the appropriate choice as a surgical knife.