The word “evolution” first appeared in the sixth edition of Darwin’s On the Origin of Species.
Darwin published the sixth edition in 1872, and it was the final major edition issued during his lifetime. In that revision he made substantial changes to the text, responded to criticisms, and added a new chapter addressing objections raised by the English naturalist St. George Jackson Mivart.
The wording can be confusing because earlier editions already used forms of the word “evolved” in their concluding passages. However, the noun “evolution” itself did not appear in the first five editions. Darwin had generally preferred phrases such as “descent with modification” when describing the process of species change.
The sixth edition also dropped “On” from the title, making it The Origin of Species. The term was already circulating in broader scientific discussion, and Darwin had used it in The Descent of Man in 1871. That makes the sixth edition the correct answer for the wording of this question, even though related forms appeared earlier.