For a mark-recapture survey, when there were 12 marked elephants recaptured to the total 130 elephants (includes both marked and unmarked) in the second capture, we know scientists have initially marked 45 elephants at the beginning.
The estimated total elephant population would be elephants based on the mark-recapture equation.

the correct answer: the index of refraction of the second medium is lower i tried this persons answer and it was wrong this person is lying

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.

answer( increase) their individual contractile activity;