Three photodiodes D1, D2 and D3

Question:
Three photodiodes D1, D2 and D3 are made of semiconductors having band gaps of 2.5eV, 2eV and 3eV, respectively. Which ones will be able to detect light of wavelength 6000 Ao?

Solution:

Wavelength = λ = 6000 Ao = 6000 × 10-10m