Final answer:
The weight of the coins is a quantitative variable for the data collected on 100 United States coins minted in 2018.
Step-by-step explanation:
In the given options, the only quantitative variable is 1) The weight of the coins. Quantitative variables are numerical measurements that represent a quantity or amount. In this case, the weight of the coins can be measured using a scale, and it can vary across the 100 United States coins minted in 2018.