In the Young's double slit experiment, the interference pattern is found to have an intensity ratio between the bright and dark fringes as 9. This implies that
(1) the intensities at the screen due to the two slits are 5 units and 4 units respectively
(2) the intensities at the screen due to the two slits are 4 units and 1 units respectively
(3) the amplitude ratio is 3
(4) the amplitude ratio is 2