I believe it is:
adjective phrase=of great price
noun modified=pearl.
Answer: It depends because altruism has many different definitions depending on what subject your studying.
Explanation: If you want to know how the term is used in daily life altruism means to be selfless. In Psychology terms altruism means a person who puts others well being before themself. In Biological terms altruism is survival of a species.
Hope this helps you hun
