Final answer:
Option (a), Psychologists guess about behavioral processes by hypothesizing, which is a crucial step in the scientific method and involves creating a testable explanation based on scientific knowledge.
Step-by-step explanation:
Psychologists make educated guesses about behavioral processes through the process known as hypothesizing. Formulating a hypothesis is a crucial step in the scientific method. It involves creating a tentative explanation for a set of observations, which can be tested through further research and experimentation.
A hypothesis must be based on scientific knowledge, be logical, and be falsifiable. For example, in understanding why we experience alternating periods of light and darkness, a hypothesis could be formulated to test the observed movements of celestial bodies like the sun and the moon.