Final answer:
Carl Sagan did not claim that two different species from two different planets can mate and produce offspring.
Step-by-step explanation:
In his book "The Case of the Ancient Astronauts," Carl Sagan did not claim that two different species from two different planets are capable of mating and producing offspring. This concept relates to the idea of interspecies reproduction, which is generally not possible due to genetic incompatibilities between different species. While Sagan did explore the possibility of extraterrestrial life in his book, he did not make this specific claim. Therefore, the answer is False.