Description acceptable. An ultra-stable superfolder GFP was created to tolerate procedures that confer this property, which often require weeks-long immersions in Triton X-100. The Scale and CUBIC protocols for producing this property may cause sample expansion, which can be controlled by embedding in a hydrogel. (-5[1])An alleged consequence of the Kramers–Kronig relations is that topically applying a strong absorber like tartrazine can cause this property in a sample. Methods in the DISCO family give 3D samples this property, (-5[1])allowing (*) microtoming to be replaced (10[1])with optical sectioning by light sheets. (10[1])Delipidation and fluid displacement by benzyl (10[1])ether gives a fixed and stained tissue sample this property in the process of “clearing.” For 10 points, what desirable property is achieved by refractive index (10[1])matching that allows imaging tissues’ internal structures? (10[1])■END■ (10[5])