Hexagonal profiled wrenches made specifically to interface with allen keyed fasteners.

• A. Grommet Tool Set
• B. Allen Wrench Set
• C. Adjustable Wrench
• D. Nail Pulling Pliers

Answer: (B)

A tool designed to fit inside the hexagonal recess of Allen-headed fasteners is the key idea here. Hexagonal profiled wrenches, known as Allen wrenches or hex keys, are shaped to match that internal six-sided socket. When you insert one and turn, you can apply torque directly to the fastener without rounding its corners, which is why these tools are preferred for Allen-keyed fasteners. A set is useful because fasteners come in different sizes, so having multiple hex key sizes ensures you can snugly fit the specific fastener you’re working with.

The other options serve different tasks: a grommet tool set is for installing grommets; an adjustable wrench handles various external-nut sizes with a movable jaw; nail pulling pliers are for removing nails. None of these are designed to interface with the internal hex recess of Allen-headed fasteners, so the Allen wrench set is the best fit.