What Data Allowed Abrahams, Robb, and Hare (2005) to Conclude

What data allowed Abrahams, Robb, and Hare (2005) to conclude that opercular flare displays are an accurate indicator of male fighting condition?

A) Flare display rate was influenced by fish body size.
B) Flare display rate was influenced by the presence of a simulated intruder.
C) Flare display rate was related to water oxygen level.
D) Flare display rate was influenced by the presence of a female observer.
E) Females preferred those males that had the highest flare display rate.