The answer is A: explicit.
Explanation for each option:
a) Explicit: This is the correct answer. Explicit memory, also known as declarative memory, involves conscious recollection of information such as facts and events. Remembering a psychology lecture from earlier in the week requires conscious effort to recall the information, which is characteristic of explicit memory.
b) External: This is incorrect. External memory is not a recognized type of memory in psychological terms. It might refer to external aids like notes or devices used to store information, but it does not describe a type of human memory.
c) Internal: This is incorrect. Internal memory is not a standard term used in psychology to describe types of memory. It might be confused with internal processes of memory, but it does not specifically categorize a type of memory.
d) Implicit: This is incorrect. Implicit memory, also known as non-declarative memory, involves unconscious recollection of skills and tasks, such as riding a bike or typing on a keyboard. It does not require conscious effort to recall, unlike remembering a lecture.