（克漏字）
Deep in the perennially misty cloud forests of Central and South America resides the Glass Frog, a creature whose survival strategy has long fascinated biologists. By appearing to have mastered the art of illusion, this amphibian remains a biological __31__ with a counter-intuitive feature. While its dorsal surface is solid green, its abdominal underside is strikingly __32__, revealing internal organs like a pulsating heart. This anatomical peculiarity facilitates "edge diffusion," allowing light to __33__ the body and making its silhouette nearly invisible against the visual complexity of the surrounding foliage.
Beyond appearance, these frogs exhibit diligent parental care. The female frog lays the eggs on a leaf underside, while the male stays behind to guard the egg clutches. Near waterway margins, these overhanging clusters, __34__ are vigilantly hydrated with the male frog's body moisture, would survive before they drop into the streams below. Interestingly, these amphibians attest to whether environmental health remains uncompromised, providing biological testimony to the ecosystem's __35__. They require unpolluted habitats, their presence signifying a thriving ecosystem.

31.
(A) fallacy

(B) enigma

(C) paradox

(D) conundrum