Let us take an example of chain. Plants are producer, they produce grass, after then it comes primary consumer like cow,goat etc. Then it comes Secondary comsumer like us, we human take milk or flesh from it. And at last it comes to decomposer which are micro organism that absorb the wastes in the soil and make the soil fertile.
The correct option is A.( Lens ) The eye piece is the part of the telescope that one looks through and is the part that makes the focused light visible to the eye. The eye piece is made up of magnifying lenses.