Final answer:
Yes, it is true. Erwin Chargaff made a key discovery leading to the structure of DNA.
Step-by-step explanation:
True. A key discovery leading to the structure of DNA was indeed made by Erwin Chargaff. In the 1950s, Chargaff's rules were established when he found that the concentration of adenine is always the same as thymine, and the concentration of guanine is always the same as cytosine, in DNA. Chargaff's rules played a crucial role in the subsequent discovery of the double-helix structure of DNA by James Watson and Francis Crick.