Correct Answer - D
Resultant intensity for two interfering waves is given by
`I_(R)=I_(1)+I_(2)+2sqrt(I_(1)I_(2))cosphi`
For maximum `cos phi` = maximum =1
i.e., `phi=0,pm2pi,pm4pi`
or `phi=pm2pin, n=0,1,2...`
`I_(max)=I_(1)+I_(2)+2sqrt(I_(1)I_(2))`
`=(sqrt(I_(1))+sqrt(I_(2)))^(2)`