Final answer:
Abraham Maslow proposing the hierarchy of needs.
Step-by-step explanation:
The notable event in psychology that occurred last is d. Abraham Maslow proposed the hierarchy of needs. Maslow was an American psychologist known for his theory of human motivation, which he represented as a pyramid-shaped hierarchy. According to Maslow, individuals are motivated by different levels of needs, starting with physiological needs (food, water, shelter) and progressing to higher-level needs such as love and self-actualization.