Teaching BPSC बिहार प्राथमिक (1 to 5) शिक्षक भर्ती 4.0 Mock Test General Knowledge Ecology and Environment Environmental pollution
Which pollution is responsible for "Knock-Knee-Syndrome"?
1
Fluoride
2
Mercury
3
Aresnic
4
More than one of the above
5
None of the above