B F Skinner Warned That There Were Certain Lifestyle or Environmental Factors

B. F. Skinner warned that there were certain lifestyle or environmental factors that contributed to a lack of intellectual growth in later life. Which of the following describes one of these factors?

A) Older people interact with too many other people every day.
B) Older people may be encouraged to spend too much time reminiscing about the past.
C) Older people are likely to live in warm climates.
D) Older people spend too much time planning for the future.