With reference to 'fly ash' produced by the power plants using coal as fuel, which of the following statements is/are correct?
- Fly ash can be used in the production of bricks for building construction.
- Fly ash can be used as a replacement for some of the Portland cement contents of concrete.
- Fly ash is made up of silicon dioxide and calcium oxide only, and does not contain any toxic elements.
Select the correct answer using the code given below.