The correct option that defines extremist ideology during the early phase of the Indian freedom movement is:

Obtaining self-government by aggressive means in place of petitions and constitutional ways

The extremists, led by leaders such as Bal Gangadhar Tilak, Bipin Chandra Pal, and Lala Lajpat Rai, believed in adopting more radical and assertive methods to achieve self-government for India. They advocated for boycotting British goods, organizing mass movements, and using non-cooperation as a means of challenging British rule. They emphasized the importance of Swaraj (self-rule) and self-reliance. Their approach was in contrast to the moderate leaders who focused on petitioning and constitutional means of seeking reforms.