Which sentence best describes Christian Rutz’s work? Question 1 options:

a. Rutz has researched why Hawaiian crows are smarter than most chimpanzees.

b. Rutz believes that New Caledonian crows are the most intelligent bird species.

c. Rutz’s work provides clues about the evolution of birds and tool use

d. Rutz has discovered that most birds are not as intelligent as crows