Which is the oldest method of plant breeding for crop improvement?

The basis of the Green Revolution is:

Which of the following is an inconsistent trait for plant breeding?

In which crops is the method of mass selection applied?

In the area of plant breeding,it is important not only to preserve the seeds of the variety being cultivated,but also to preserve all its wild relatives. Explain with a suitable example.

In $1960$,the wheat production revolution in India was made possible due to which of the following?