Emasculation(removal of anthers) is required for

1. Pure lines
2. Slective hybridisation
3. Self pollination
4. Inbreeding

The correct option is 2.
During hybridization, fertilization has to be done by pollen from a desired parent plant. In plants having separate male and female flowers on the same plant as in maize coconut etc., the male flowers are removed. The removal of male parts from bisexual or male flowers is called emasculation.