Photons absorbed in matter are converted into heat. A source emitting ‘n’  photons per second of frequency ‘$\nu$ ’ is used to convert 1kg of ice at 0°C to  water at 0°C . Then the time ‘T’ taken for the conversion 

Energy spent to convert ice into water 
=mL=(1000g)×80calg⁻¹=80000 cal
Energy of photons used = nT×E=nT×hν
$\therefore \mathrm{nTh\nu }=\mathrm{mL} \mathrm{or} \mathrm{T}=\frac{\mathrm{mL}}{\mathrm{nh\nu }}$
∴   T∝ν^-1​  when n fixed. Thus T is constant if ν is constant . Thus options(a), (b) and (c) are correct.