Answer: Hello your question is open ended hence I will provide a more general answer
answer : Use of systematic sampling method
Explanation:
To obtain a representative sample of pebbles ( more representative sample ) Leaners should use <em>Systematic sampling method</em> . This is because systematic sampling covers the the entire population by obtaining samples from the population of pebbles at regular intervals hence it is a more comprehensive system of sampling when compared to Random and stratified sampling
