The correct answer is: A. Faulty tools of measurements
Sampling error is the difference between the estimate from a sample and the true value in the population. It is caused by chance variation in the sampling process.
Faulty tools of measurements are not a cause of sampling error. They are a cause of measurement error. Measurement error is the difference between the observed value and the true value. It is caused by factors such as the instrument used to measure the variable, the person who is measuring the variable, and the environment in which the measurement is taken.
Inadequate sample, non response, and defect in data collection are all causes of sampling error.
Inadequate sample is a sample that is not representative of the population. This can happen if the sample is too small, if the sample is not randomly selected, or if the sample is biased.
Non response is when some members of the population do not participate in the survey. This can happen if the members of the population are not available, if they are not interested in participating, or if they do not trust the survey.
Defect in data collection is when there is an error in the way the data is collected. This can happen if the questions are not clear, if the answers are not recorded correctly, or if the data is lost or destroyed.