would a trait that has only two distinct phenotypes more likely be a single-gene trait or a polygenetic trait? How do you know? plz, hurry! will give brainiest

weathering - colorado river carves land in arizona to form the grand canyon. cracks form in a sandstone wall surrounding a house. a marble statue near the science museum is changing color due to rainfall

erosion - after a rainstorm, soil and rock piees litter the roadways. the sand dunes in the sahara desert are changing shape.

here's your answer.