In the 1974 Study by Alan Baddeley and Graham Kitch

In the 1974 study by Alan Baddeley and Graham Kitch, subjects were required to recall a series of digits while reasoning or comprehending the meaning of sentences. Their results suggest that working memory is more than a single system and are supported by which ONE of the following?

A) Holding 4-8 digits in memory decreased the time to solve the reasoning task.
B) A memory load of 3 items did not affect reasoning speed.
C) Reasoning accuracy greatly impaired recall accuracy.
D) none of the above