In sampling and data collection for scale construction, a researcher must ensure that:

A) the sample is of convenience.
B) the size of the sample is appropriate.
C) the sample has high statistical validity.
D) the randomness of the sample is as low as possible.

The size of the sample is important for scale construction because a larger sample size generally increases the accuracy and precision of the results. Adequate sample size depends on the research question, population size, sampling method, and statistical power requirements, among other factors. The sample should also be representative of the population of interest to ensure external validity, but this is not the same as statistical validity. The randomness of the sample should be as high as possible, meaning that each member of the population has an equal chance of being selected, to reduce selection bias and increase the generalizability of the findings. Convenience sampling should generally be avoided because it may result in biased or non-representative samples.