Why Is the Mass of Earth Important for Life

Why is the mass of Earth important for life?

A) If Earth had more or less mass, it would not have plate tectonics and would be covered entirely by water.
B) If Earth's mass were greater, we would be bombarded by meteorites and if it were smaller, we would not be able to hold the moon in orbit.
C) If Earth had more or less mass, the atmosphere would be very different with either too much ammonia and methane or too little oxygen and water.
D) If Earth's mass were significantly different, we would be bombarded by cosmic rays that would strip away our atmosphere.