Two source `S_1` and `S_2` of intensity `I_1` and `I_1` are placed in front of a screen [Fig. (a)]. The patteren of intensity distribution seen in the central portion is given by Fig. (b). In this case which of the following statements are true.
Options:
(a) `S_1` and `S_2` have the same intensities.
(b) `S_1` and `S_2` have a constant phase difference.
(c) `S_1`and `S_2` have the same phase.
(d) `S_1`and `S_2`have the same wavelength