(c) XB​>XA​,XB​>XC​Wavelength of light B is 555 nm. It has the highest luminosity; hence, XB​ will be highest. Again, 450 nm is nearer to 555 nm than 700 nm.∴ 555-450=105But 700−555=145So, XA​'s brightness will be greater than that of XC​.