The work functions for metal $\mathrm{a}, \mathrm{b}$ and c are respectively $1.92 \mathrm{eV}, 2.0 \mathrm{eV}$ and 5 eV. According to Einstein's equation the metals which will emit photoelectrons for a radiation of wavelength $4100 Å$ is a/are:

• A

  none
• B

  'a' only
• Correct answer
  C

  'a' and 'b' only
• D

  all the three metals

Hence, the correct answer is option: 'C'.