The answer is (c).
The question was:
Which of the people in this photo is Joe Bizzarro, author of the study “A Review of the Physical and Biological Characteristics of the Bahía Magdalena Lagoon Complex (Baja California Sur, Mexico)“?
a) the beardless man holding the dark fish
b) the light-bearded man holding the brown fish
c) the dark-bearded man standing behind and between the beardless man holding the dark fish and the blonde woman holding the curved fish
d) the blonde woman holding the curved fish
(Thanks to investigator Tom Gill for bringing the study to our attention.)