18. please help

A group of students investigates interference patterns. The students use a green diode laser to direct green light through a diffraction grating and onto a ruler placed a fixed distance behind the diffraction grating. The students adjust the position of the ruler until the central maximum of the interference pattern strikes the zero position on the ruler and observe the following pattern. Central maximum 2 21 25 20 0 cm 10 15 20 25 30 The students continue the investigation by performing two additional trials. Trial One The students replace the green diode laser with a red diode laser, repeat the procedure, and observe the pattern that is created on the ruler. Trial Two The students replace the diffraction grating with one whose lines are spaced much closer together. The students use the green diode laser to repeat the procedure and observe the pattern that is created on the ruler. 18, Which of the following patterns should be observed? The statement above is best completed by the answers in row Row Observation for Trial 1 Observation for Trial 2 O O