Food Chain

Yolanda made the simple food chain shown below.

Food Chain
Sunlight $\rightarrow$ Grass $\rightarrow$ Rabbit $\rightarrow$ ? $\rightarrow$ Lion $\rightarrow$ Bacteria

Which organism BEST completes this food chain?
A. Lamb
B. Jackal
C. Zebra
D. Oryx
E. Firefly