During a life science unit, an elementary teacher places several sprouting bean plants in a windowless closet. She places a grow light so that the light shines on the plants from the right side. Students observe the growth of the plants for one week. The following week, the teacher moves the lamps to the left side of the plants. The students observe that the plant stems lean to the right during the first week and lean left during the second week. These results best demonstrate that -
a) Plants prefer light from the right side.
b) Plants lean toward the direction of the light source.
c) Plants always grow straight up.
d) The grow light has no effect on plant growth.
