Answer:
Convenience Sampling
Step-by-step explanation:
Since in the given case items are not selected randomly for sampling, neither any groups or clusters are created, this form of sampling is not random sampling or clustered sampling.
Sampling refers to the technique of arriving at a conclusion by selecting n number of items and the results obtained from observation of those selected n number of items shall be representative of the entire population.
There are two forms of sampling namely probability and non probability forms of sampling.
The quality control officer in this case applied convenience sampling wherein observations are chosen as per the availability and convenience. Likewise in the present case, first 100 mattresses which were manufactured were taken up for sampling.
This is a non probability form of sampling.