Consider the following statements regarding cell inclusions and choose the correct answer:
1. Starch grains occur in plant cells only, particularly in storage organs such as rhizomes and tubers
2. Aleurone grains contain stored proteins in plant cells
3. Crystals of various chemical compounds occur in plant cells

A. Only 1 and 2 are true

B. Only 2 and 3 are true

C. 1, 2 and 3 are true

D. None of them is true

Answer: Option C