A three-dimensional graphic foil embedded in the check to provide additional protection against duplication is known as what?

A three-dimensional graphic foil embedded in a check to prevent duplication is known as a foil hologram. This type of security feature is designed to be difficult to replicate and adds a layer of protection against forgery and counterfeiting. Holograms exhibit a three-dimensional appearance that changes depending on the angle of light and viewer position, making them visually distinctive and easily recognizable.

In contrast, the other options do not specifically refer to the three-dimensional nature intrinsic to holograms. A colored pantograph is typically a method for reproducing images but doesn't indicate a three-dimensional effect. A prismatic multicolored background may involve color variations, but it lacks the depth and light-reflective properties that define holograms. A thermochromic heat-sensitive icon refers to materials that change color with temperature, which is not relevant to the optical and security functions of a hologram. Thus, the foil hologram stands out as the correct identification of the feature that enhances security in checks.