Given below are two statements: 

Two Sources ${\mathrm{S}}_1 \mathrm{and} {\mathrm{S}}_2$ of intensity $I_1 and l_2$ are in front of a screen [Fig.(a)]. The pattern of intensity distribution seen in the central portion is given by Fig.(b).

In this case, which of the following statements are true?

(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 

1. (a, b, c)

2. (a, b, d)

3. (b, c, d)

4. (c, d)

Assertion: For best contrast between maxima and minima in the interference pattern of Young's double slit experiment, the intensity of light emerging out of the two slits should be equal.
Reason: The intensity of the interference pattern is proportional to square of amplitude.

1. Both the assertion and the reason are true and the reason is a correct explanation of the assertion.
2. Both the assertion and reason are true but the reason is not a correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both the assertion and reason are false.