Robert Notices That Several Respondents Did Not Answer the Question

Robert notices that several respondents did not answer the question of whether they took out loans to fund their education.However,later in his survey,Robert finds that respondents told him about the source(s)and the amount(s)of their college loans.In handling the missing data on the question of whether or not they had a college loan,Robert's best approach is to:
randomly assign values to the missing data
delete the cases with missing data from the analysis
assign the middle value to the cases with the missing data
use the latter information about amount and source of loans as grounds for assigning values to the cases which had missing values
all of these choices are equally appropriate