Final answer:
A psychologist using careful observation, formulating hypotheses, and conducting experiments to solve a problem is utilizing the scientific method. The correct answer is a) The scientific method.
Step-by-step explanation:
When a psychologist decides to solve a problem by collecting data through careful observation and formulating a hypothesis, they are using the scientific method. This method is a systematic approach that starts with an observation, proceeding to formulating a question, followed by research and the development of a testable hypothesis. The psychologist then conducts experiments and analyzes the results to draw conclusions.
This process often involves both qualitative and quantitative observations, and aims at gaining empirical evidence to support or refute the hypothesis. The scientific method is a systematic approach that involves making observations, forming hypotheses, designing experiments, and analyzing the results to draw conclusions. Therefore, the correct answer is a) The scientific method.