What became useful in the increased production of food thousands of years ago?

Which of the following is the first fungicide?

Consider the following statements:
$I$. Solid stem in wheat exhibits non-preference by stem sawfly.
$II$. In cotton,smooth leaf and absence of nectar repel bollworms.
$III$. In maize,high aspartic acid,low nitrogen and sugar content protect them from stem borers.
Which of the statements given above are correct?

Select the mismatched pair from the following.

Which three crops contribute the most to global food production?

For which of the following requirements has humanity been active since the beginning?