What does the term 'eutrophic lakes' mean?

For $3$ wheelers vehicles,which emission norm was implemented throughout the country since October $2010$?

What is the amount of oxygen consumed by bacteria to oxidize all the organic matter present in one liter of water called?

Define/Explain: Noise.

Which of the following statements are correct regarding Eutrophication?
$I-$ Streams entering into a lake introduce nutrients like nitrogen and phosphorus,which encourage the growth of aquatic organisms.
$II-$ As the lake's fertility increases,plant and animal life flourish.
$III-$ Organic remains begin to deposit at the bottom of the lake.
$IV-$ Organic waste materials continue to accumulate in the lake.
$V -$ The lake becomes shallower and warmer.
$VI -$ Cold-water organisms are replaced by warm-water organisms.
$VII -$ Marsh plants take root in the shallows and begin to fill in the original lake basin.

What does a high $BOD$ of water indicate?