Virginia and her brother William disagree over when their father was born: Virginia claims it was in 1935 and William claims it was in 1933. The hospital where their father was born has no records for 1933 but has complete records for 1935 -- records that do not include a birth record for their father. Ttherefore, he must have been born in 1933. The argument depends on which of the following assumptions? ['The records of the hospital where their father was born date back to 1933.', "Virginia and William know the day and the month of their father's birth.", "There was urgent practical reasons why Virginia and William must know the date of their father's birth.", "Either Virginia's claim or William's claim is correct."]