In Testing a Hypothesis That "Territorial Defense in European Robins

Multiple Choice

In testing a hypothesis that "territorial defense in European robins is a fixed action pattern that is released by the sight of orange feathers," researchers found that robins defended their territory by attacking anything that was of similar size and had an orange patch.How would you show that it was indeed color that initiated the defense responses?

A) Repeat the experiment using live specimens.
B) Repeat the experiment using other shapes.
C) Repeat the experiment removing the orange patch.
D) Repeat the experiment with giant specimens.