Which of these is a case of selective breeding?

Question 4 options:

Over time, more milk cows at the diary farm began to produce larger amounts of milk.


A gene was identified that increased milk production. This gene was added to calves in the womb.


The genome of a group of cows was analyzed to identify the gene for milk production.


To increase the production of milk in a herd of milk cows, the highest producing cows were chosen as the mothers.