The correct option is (a) Percolating filter
The best I can explain: Percolating filter, in which the waste trickles and which is oxidized and hence removed by biological degradation, Filter cake is the by-products of filtration left on the surface forming cakes, In-situ bioremediation involves certain techniques like Biosparging, Bioventing and Injection recovery whereas bioluminescence is an inherent light emitting property of biological organisms.