In the scenario of sealing a house plant in a transparent glass container, the most likely factor that would lead to the plant's death is a lack of carbon dioxide.
While the plant can initially use the carbon dioxide present in the sealed environment for photosynthesis, it will eventually deplete this resource if no new carbon dioxide enters the system. Eventually, without a continuous supply of carbon dioxide, the plant cannot photosynthesize effectively, leading to its death.
It's worth noting, however, that a lack of light would also be detrimental to the plant's survival in the long run, as plants require light for photosynthesis. But if we consider the immediate and continuous factors influencing death, the depletion of carbon dioxide is critical.