The diagram illustrates part of the nitrogen cycle. Which row correctly names the bacteria involved in processes W, X, Y and Z?
- AW denitrifying; X decomposer; Y nitrifying; Z nitrogen-fixing
- BW denitrifying; X nitrifying; Y decomposer; Z nitrogen-fixing
- CW nitrifying; X decomposer; Y nitrogen-fixing; Z denitrifying
- DW nitrogen-fixing; X nitrifying; Y decomposer; Z denitrifying