Answer:
a. a parameter.
Step-by-step explanation:
A parameter is a property that describes the whole population, while a statistic is a property pertaining to a sample or sub-set of the population.
In this example, the average content of 4 ounces pertains to the 121 bottles sample and thus is a statistic. While the standard deviation of the population is mentioned to be 0.22 ounces, therefore 0.22 is a parameter.