The correct answer to this question is C, Grass. There are many types of measurements used in fields such as astronomy and climatology. Albedo is one of those measurements. It measures how a surface reflects solar radiation. Measured on a scale from 0 to 1, albedo has no dimension.
A low albedo means a small amount of radiation is indicated on the surface, and much of it is absorbed. Grass reflects less than 20% radiation, which is why it is the lowest. Though not as low as grass, other surfaces that have a lower albedo include water (specifical ocean) and asphalt.
Do you know what an albedo is? It will be hard for you to answer this question when you barely know what this is. This is the energy that comes from the sunlight that is sometimes reverted back to the atmosphere. According to different studies, this will have an impact on the type of climate that we are experiencing right now.
Out of the following, the one with the lowest albedo has to be C. Grass is known to be bad at reflecting different objects. This is opaque and the color makes it hard for the sun to pass through. If the color of grass is different, the albedo rate may be different as well.