Final answer:
Wundt concluded that simultaneous mental activities are not possible based on psychological experiments involving introspective analysis under controlled conditions in his laboratory, thus selecting A) Psychological experiments as the correct answer.
Step-by-step explanation:
Wilhelm Wundt concluded that a person cannot engage in more than one mental activity at the same moment based on psychological experiments conducted in his laboratory. Wundt used a controlled experimental method involving introspective analysis, which he believed could be made sufficiently scientific if it was conducted under controlled conditions. Therefore, the correct answer to the question is A) Psychological experiments. Wundt's experimental approach involved careful measurement, such as calculating reaction times to stimuli like lights, images, or sounds, to explore the structures of the mind. This methodology is considered as one of the foundations of modern psychology and helped establish the discipline as distinct from philosophy and neurology.
His approach was directed by the concept of structuralism, which sought to decompose the mind's complexity into its simplest elements. Such experiments were a cornerstone of Wundt's approach to understanding conscious experience, inherently arguing against the possibility of multitasking at the level of conscious thought processes.