The relationship that most likely reflects both correlation and causation is: "When a family goes to the park more often, they get more fresh air."
This is because going to the park typically involves outdoor activity, which directly leads to increased exposure to fresh air. In this case, the increase in time spent at the park (correlation) directly causes an increase in the fresh air they receive (causation). The other options imply correlation but do not clearly indicate a direct causal relationship.