Final answer:
Parker Selfridge justifies the attack on the Na'vi's Home Tree as a move driven by Economic interests, specifically the extraction of the valuable mineral Unobtanium.
Step-by-step explanation:
In the 2009 film Avatar, Parker Selfridge justifies attacking Home Tree to Grace with B) Economic interests. His motivation for the assault is largely based on the valuable mineral Unobtanium, which is found in large quantities beneath the Na'vi's Home Tree. Parker is driven by the potential profits this mineral could bring, and the attack is portrayed as a corporate decision rather than one based on military strategy, Na'vi aggression, or the Avatar program success.