What is the quickest method to collect primary data?
A) Personal Interview
B) Indirect Interview
C) Mailed Questionnaire Method
D) Telephonic survey

Hint: In this question we are given four options and we have to choose which one is the quickest method to collect primary data. Analyze the meaning of the options one by one and decide which is the quickest.

Complete step-by-step solution:
We have been asked to choose the quickest method to collect primary data. Let us first know about all four of them in brief.
1) Personal interview- In this, the researcher or investigator conducts the face to face interviews with the person. This is the most preferred interview over others as in this, the person gets the chance to explain himself and his answers. The investigator can judge the honesty through his facial expressions and personality. Misinterpretation and misunderstanding can be avoided in this.
2) Indirect interview- In this, data is collected from indirect sources. The persons who are expected to have knowledge about the problems are interrogated and on the basis of their answers, the data is compiled. The accuracy of the data collected by this method is unknown and this type of interview is not so fast.
3) Mailed questionnaire method- In this, the questionnaire is sent to each person through mail and they are requested to complete the questionnaire and mail them back before specified time and date. This method is not at all expensive. However, it is not reliable or fast because of the lack of internet facilities in backward areas and many times, people do not even respond.
4) Telephonic survey- In this, interviews or surveys are conducted over a phone call. This method does not work in some areas because of the lack of telephones. However, it is a good method to collect information especially on some sensitive issues as the interrogator and the person cannot see each other.
Now, as we can notice that the telephonic interview does not require anybody to travel or spend some money, it is the fastest method to collect primary data.

Option D is the correct answer.

Note: We solved this problem by trial and error method, so we have to know about the trial and error method
Trial and error refers to the process of verifying that a certain choice is right (or wrong). We simply substitute that choice into the problem and check. Some questions can only be solved by trial and error; for others we must first decide if there isn't a faster way to arrive at the answer.
Students might also think that the personal interviews can be fastest. However, it requires people to travel and meet at a common place. Hence, it is not the fastest.