Answer: c) Theory of mind
Step-by-step explanation:
According to the concept of Premack and Woodruff, theory of mind depicts about mental state of chimpanzee that is observed and studied that indicates that they have some realization of intention, purpose and thinking
Other options are incorrect because performance of object, imprinting , crystallized intelligence or conservation are not the phenomena that define capability of the chimpanzees for know intentions of others .Thus, the correct option is option(c).