A new plant species has a unique photosynthetic pigment. The leaves of this plant appear to be blue-green. What wavelengths of visible light does this pigment reflect

Blue and green wavelengths

Explanation:

A pigment is any substance that can absorb specific wavelengths of light , reflecting light not absorbed. Wavelengths of lights not absorbed and therefore reflected gives the color of pigment.

Chlorophyll, the green pigment is common to all plant cells, meaning that it absorbs all wavelengths of visible light leaving  green, which we can see as it is reflected.

In the same vein, any plant appearing blue-green means that the pigment of the plant specie has absorbed all wavelengths of the visible light except the blue -green which it reflects and detectable by our eyes.