| both naturally | 5 | manner |
| by heating natural gas | 5 | manner |
| to photosynthesis inhibition | 4 | cause |
| ethylene → be → produced | 20 |
| ethylene → be produced in → response | 3 |
| ethylene → be → derived | 3 |
| negative | neutral | positive |
| 0.161 | 0.780 | 0.059 |
| Raw frequency | 26 |
| Normalized frequency | 1.000 |
| Modifier score | 0.500 |
| Perplexity | 316.628 |