A decline in direct interpersonal interaction is known to precipitate depressive symptoms. Hours devoted to online gaming are hours unavailable for direct interpersonal interaction, so researchers have hypothesized that a sudden escalation in gaming can produce depressive symptoms. Surveys of habitual gamers have found a markedly higher rate of depressive symptoms among those who had recently tripled their weekly gaming hours than among those whose gaming time had held steady. The researchers' hypothesis is therefore confirmed.

The argument depends on which of the following?

A. In general, the reason that the surveyed gamers had tripled their gaming hours was not that they had previously suffered a substantial reduction in opportunities for direct interpersonal interaction.
B. A sharp reduction in direct interpersonal interaction is the sole alteration in daily routine capable of elevating the rate of depressive symptoms.
C. Gaming affords no avenue by which players might increase the amount of direct interpersonal interaction in their daily lives.
D. Habitual gamers who are already experiencing depressive symptoms will see their mood improve at once if they abruptly curtail their weekly gaming hours.
E. Prior to tripling their gaming hours, the surveyed gamers were already more susceptible to depressive symptoms than are habitual gamers generally.