Final answer:
Adolescents experience an intellectual change where they develop complex thinking abilities, allowing them to engage with abstract concepts and questions, corresponding to option (d) from the list provided.
Step-by-step explanation:
During adolescence, one mental or intellectual change is the development of the ability to engage in more complex thinking and to handle abstract concepts such as freedom, justice, and ethical questions. This shift to abstract thought enables adolescents to explore and ask broad questions about the meaning of life, which corresponds to option (d) as the answer to the student's question. These changes are a part of cognitive development, where teenagers improve on existing logical and problem-solving skills, and are able to consider multiple points of view and imagine hypothetical situations.
Psychosocial development also takes place, where adolescents refine their sense of self and question authority or societal norms. This is related to Erik Erikson's theory of identity versus role confusion, as individuals in this age group strive to define 'Who am I?' and 'What do I want to do with my life?'