Despite having the highest overall GDP, the US ranks fifth for productivity when considering the GDP per hour worked. What contributes to this discrepancy?

A: People in the US are more easily distracted than workers in other countries.
B: The US has more people, and so less output is needed.
C: The US has the longest average work week among the top 10 countries.
D: People in the US do not work as hard as workers in other countries.