Question

which is a source of land pollution? heavy traffic producing large amounts of exhaust mold growing on an indoor windowsill people smoking tobacco outside a building fertilizer running off from a large agricultural farm

Explanation:

Land pollution involves substances that contaminate the land. Heavy traffic exhaust is air pollution. Mold on a windowsill is a local indoor issue not widespread land pollution. Smoking outside is more of an air - related (and local) concern. Fertilizer runoff from a farm can contaminate large areas of land (and also water, but the runoff itself starts as a land - based pollution source as fertilizers are applied to land).

Answer:

fertilizer running off from a large agricultural farm