In a recent study, each member of two groups of people, Group A (composed of persons sixty-five to seventy-five years old) and Group B (composed of college students), was required to make a telephone call to a certain number at a specified time. The time when each call was initiated was recorded electronically. Group A proved far better at remembering to make a telephone call precisely at a specified time than did Group B. There were fourteen lapses in Group B but only one lapse in Group A. Clearly, at least one type of memory does not suffer as a person ages. Which one of the following, if all of them are true, is LEAST helpful in establishing that the conclusion above is properly drawn? ['The members of the two groups received their instructions approximately the same amount of time before they were to make their telephone calls.', 'The same group of researchers answered the calls made by the callers in both study groups.', 'Both groups had unrestricted access to telephones for making the required calls.', 'There was the same number of people in each group.']