Final answer:
The Olsen-Hegar is the instrument that functions as both a needle holder and scissors, utilized frequently in surgical procedures for efficiency.
Step-by-step explanation:
The instrument that is a combination of a needle holder and scissors is the Olsen-Hegar. This medical tool is commonly used in surgical procedures and allows the user to both hold the needle and cut suture materials without the need to switch instruments. Unlike the Olsen-Hegar, the Mayo-Hegar is strictly a needle holder, the Rochester-Carmalt is primarily for grasping and clamping large tissue bundles, and the Brown-Adson is a type of tissue forceps known for its fine tips for precise tissue handling.