Which of the following can upset the balance of an ecosystem?
too much water
not enough water
too much light
not enough light
all of the above
none of the above

All of the above.

Explanation:

Light and Water both are among the ecological factors .Ecological factors are those components of environment which determine the variation in the chemical and physical nature of different ecosystem.A balanced ecosystem needs to have all its ecological factors in adequate amount.Thus, too much water, too much light, not enough light or not enough water , any of these condition can upset the balance of ecosystem.