Final answer:
The aspect of consciousness that describes Abby's simultaneous awareness of her textbook and an external conversation is known as 'content of awareness'. option d.
Step-by-step explanation:
The aspect of consciousness that describes Abby's awareness of both her textbook material and the conversation is d. content of awareness. This term refers to the various internal and external stimuli that we are aware of at any moment. In Abby's case, she is aware of the content of her textbook as she reads (internal focus), as well as the conversation of the group of girls (external stimuli), highlighting her ability to process different streams of information simultaneously and be conscious of multiple aspects of her environment. This term refers to the various internal and external stimuli that we are aware of at any moment.