Answer:
all the phones produced during the day in question.
Step-by-step explanation:
Okay, we are given the following data or information or parameters in the question above and they are; 2 % of the phones produced per day are defective, the quality of a day's production was checked by sampling 50 samples randomly.
Therefore, the best option or Explanation that best Define the population of interest to the manufacturer is; ''all the phones produced during the day in question''.
Also, the 50 phones that are sampled randomly and 2% which are defective is a condition that the manufacturer should be interested in.