In any closed ecosystem, if we put some snails and some plants in them, the snails would survive for a while but next day they will die, this is because of the reason that the snails can survive for a while in closed ecosystem but the waste products which takes place in the ecosystem due to both the plants as well as the snails affects the snails due to which they are likely to die soon.
The reason why the snails are dead because the snails lack oxygen for it is a model of closed ecosystem. Another reason to this is that they lack abiotic factors that they need in surviving or as they live for the place that they are living lacks a lot and are not enough for them to last or survive. Lastly, the water could have not been a contributor for them to live for they may not be able to live in a water environment and could only dwell in land.
The statement that describes how work and power are similar is D. you must know time and energy to calculate both. I am not completely sure though, so I hope this helps. :)
