What must the path difference between two coherent light sources of wavelength $2$ be for destructive interference to occur at a point where the two waves meet?$2,$ where i is an even integerb$)(1)/(2)2,$ where n is an odd integerc$)$ n$2,$ where n is an even integerd$)$ ni$,$ where n is an odd integere$)$ n$2,$ where n is any integer