Final answer:
The mode of travel to California during the Gold Rush that was not available was the Panama Canal transit, as the Transcontinental Railroad was completed later. The correct option is B. Panama Canal transit
Step-by-step explanation:
The correct answer to which one of the following was not a method of traveling to California during the Gold Rush is option B: Panama Canal transit. During the California Gold Rush, overland wagon trains were a common method of transportation as people traveled across the continent on foot, on horseback, or in wagons.
Passage around Cape Horn was another way people reached California, involving a long sea voyage around the southern tip of South America. Another popular sea route involved sailing to the Isthmus of Panama, crossing it, and then booking passage by ship to San Francisco.
However, the Transcontinental Railroad was not yet completed during the Gold Rush era; it was finished in 1869, whereas the Gold Rush peak was from 1848 to 1855. Hence, travelers could not use the Transcontinental Railroad to reach California during the Gold Rush. The correct option is B. Panama Canal transit