Refer to the given flow chart and select the option that correctly identifies organisms P, Q, R and S.

| P | Q | R | S | |
|---|---|---|---|---|
| A | Hydrilla | Hydra | Dionaea | Amoeba |
| B | Hibiscus | Taenia | Bladderwort | Croton |
| C | Elodea | Cuscuta | Rhizopus | Gambusia |
| D | Ocimum | Coleus | Mistletoe | Spirogyra |
and for lighting
, we need _____.