When did Sam start experiencing allergy symptoms?

The correct answer indicates that Sam began experiencing allergy symptoms after entering the house. This suggests a probable connection between the indoor environment and the onset of his symptoms. Allergies can often be triggered by indoor allergens such as dust mites, pet dander, or mold, which are typically more prevalent inside homes.

The other scenarios, like riding bikes, playing tag, or being before arriving at Josh's house, do not specifically imply a factor that would initiate allergy symptoms in the same way. Outdoor activities can expose someone to pollen or other environmental allergens, but without context pointing directly to the home environment, the symptoms are less likely to be attributed to those situations. Thus, indicating that his symptoms began upon entering the house effectively highlights the potential impact of indoor allergens on allergy sufferers.