Consider the following structures
Which of the pairs represent D and L-fructose, respectively?

• A

  II and I
• B

  I and III
• Correct answer
  C

  III and IV
• D

  II and IV

Solution

Relative position of $-\mathrm{OH}$ at $\mathrm{C}_5$ defines $\mathrm{D}$ or $\mathrm{L}$ configuration.

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