'It has not rained since he's been here/he got here/his arrival.'

[tom3m]

'It has not rained since he's been here/he got here/his arrival.'
The sentence is from an exercise from 'Ready for CAE' textbook. The aim of the exercise was to recognize which form is correct. I completely failed doing this. Apparently, all of them are correct. However, I don't know why and what they mean, especially the difference between the first two. Do they mean the same thing or are they different? How?

Thanks in advance

[Rover_KE]

They all mean the same.

[MikeNewYork]

'It has not rained since he's been here/he got here/his arrival.'
The sentence is from an exercise from 'Ready for CAE' textbook. The aim of the exercise was to recognize which form is correct. I completely failed doing this. Apparently, all of them are correct. However, I don't know why and what they mean, especially the difference between the first two. Do they mean the same thing or are they different? How?

Thanks in advance

I agree with Rover.