Final answer:
The psychologist in the scenario is practicing consumer psychology, which focuses on understanding consumer behavior in the market, including attitudes toward credit purchases.
Step-by-step explanation:
A psychologist conducting a survey to obtain information for a mail-order company about current public attitudes toward credit purchases is practicing d) Consumer psychology. Consumer psychology is a branch of psychology that studies the behavior of consumers in the marketplace, including their emotional, mental, and behavioral responses to products and services, marketing, and retail environments. It differs from clinical psychology, which focuses on mental health and personal development, industrial-organizational psychology, which applies psychological concepts to workplace environments, and counseling psychology, which involves helping people with physical, emotional, and mental health issues. The survey method mentioned is a common tool used by psychologists to collect data, as it allows for information to be gathered from a large number of people relatively quickly and efficiently.
Thus, the proper application of this area of psychology pertains to consumer habits and preferences, specifically regarding credit purchases. By understanding public attitudes, consumer psychologists can contribute valuable insights to companies on how to better market their products and tailor their services according to consumer preferences and economic trends.