Question

what are the two main causes of variation ?

Answer 1

the two main causes of variation are:-

1) environment:- the sudden change of environment some organisms who used to live only one kind of environment face a lot of problems in changing temperature.

2) variation caused by genetic factors for example eye colour

Answer 2

in direct variation ,
when increases cause in x led to automatically increases in y then it is said to be in direct variation .
in inverse variation,
when increases cause in x led to corresponding decrease in y then it is said to be in inverse variation.