Teaching BPSC बिहार प्राथमिक (1 to 5) शिक्षक भर्ती 4.0 Mock Test General Knowledge Ecology and Environment Environmental pollution
What does water's high biological oxygen demand (BOD) indicate?
1
High level of microbial pollution
2
Low level of microbial pollution
3
Absence of microbial pollution
4
More than one of the above
5
None of the above