A red laser beam is incident on a double slit, creating a pattern of light and dark spots on a screen some distance away. What will happen to the pattern on the screen if the following changes are made?

(a) The distance between the two slits is increased:

1. The dots get further apart
2. The dots get closer together
3. The spacing between the dots is unchanged

(b) The red laser is replaced by a green laser:

1. The dots get further apart
2. The dots get closer together
3. The spacing between the dots is unchanged

(c) The screen is moved closer to the double slit:

1. The dots get further apart
2. The dots get closer together
3. The spacing between the dots is unchanged

(d) The entire apparatus is submerged in water:

1. The dots get further apart
2. The dots get closer together
3. The spacing between the dots is unchanged