The various types of sources used to determine the purpose of Roosevelt's autobiography created problems because

The answer is choice b

Compared to alcohol, are often more likely to produce dizziness and confusion before significant loss of physical coordination.
d. benzodiazepines

Psychologists often talk of the magical number "7" - so it is generally assumed that we can keep 7 (more or less, so 5-9 is the correct answer) items in our short term memory - we know this as a result of many experiments.

we can increase this by chunking, so for example "7 8 9 5 3" is harder to remember than "78 95 3" - try it yourself!

the answer is a)