Does anyone know what the answer is

The part of the eye that closes and opens to let light in is .

The us council on environmental quality, the world wildlife fund of the united states, the ecological society of america, the smithsonian institution, and the international union for the conservation of nature have proposed four principles of wildlife conservation. which of the following does not apply to wildlife conservation? a) continuous monitoring, analysis, and assessment b) ecosystem maintenance that includes wildlife c) a plan encompassing entire communities of organisms and all renewable resources d) a continued interest in harvesting populations for sport

What are the subsystem of the earth