MCQOPTIONS
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				| 1. | 
                                    The ratio of oxygen available to the oxygen required for stabilisation of sewage is called the | 
                            
| A. | bacterial stability factor. | 
| B. | relative stability. | 
| C. | biological oxygen demand (BOD). | 
| D. | oxygen ion concentration. | 
| Answer» C. biological oxygen demand (BOD). | |