A scientist studying soil acidity collected soil samples from a plot of land with a stream running through it. The soil samples came from land located on only one side of the stream. What is the potential source of bias that might result from the sampling method?

You find a mysterious, dull substance on the ground and pick it up for a closer look. it is powdery, very light, and soft to the touch. the substance is most likely i. an organic mineral ii. a metallic mineral iii. a nonmetallic mineral i only ii only iii only i and ii i and iii