The energy of a photon of wavelength (λ) is given by the expression: (Symbols have their usual meaning)

$hλ^{-1}c$

The correct answer is Option (3) → $hλ^{-1}c$

The energy of a photon is related to its frequency $f$ by Planck's relation:

$E = h f$

Since $f = \frac{c}{\lambda}$, where $c$ is the speed of light and $\lambda$ is the wavelength:

$E = h \frac{c}{\lambda}$

Energy of a photon: $E = \frac{h c}{\lambda}$