According to erik erikson's theory of personality development, the core strength of old age is emotional intelligence

I believe the answer is: Wisdom

Wisdom influences our ability to use the knowledge that we have in order to make a good judgment.

As we got older, our brain's function will deteriorate. But, older people tend to accumulate more experience compared to the younger ones.  Those experiences will provide older people with knowledge that might not be known by younger people. They could use it as a core strength to make better judgments than younger people.

the correct answer on edgen is:

(c.) prevent the spread of communism.

i just took the test.