Answer :
The second alternative is correct (B).
"Gold in California ignited interest in a railroad to reach the West. However, Americans disagreed on where to build the railroad."
The use of the conjunction "however" in this context connects the two sentences with a contraposition, giving the exact meaning for the continuity of the text. In this way, it became clear that there was a need to build a railroad, but there was no unity among Americans about where to build the railroad.
Answer:
B). Gold in California ignited interest in a railroad to reach the West. However, Americans disagreed on where to build the railroad.
Explanation:
Transition words are demonstrated as the words that reflect the relation or connection between phrases or sentences and aids to offer a connected thought. It aids to prevent abrupt disconnection and keeps the flow of ideas intact among the sentences.
In the given sentence, option B as mentioned above proposes a unified meaning to the sentence through the use of transition word 'however'. The assertion includes that "Gold in California ignited interest in a railroad to reach the West" but "Americans disagreed on where to build the railroad" which could best be connected through the transition 'however' as it comprehends the meaning of the sentences by aptly linking two thoughts together. Thus, option B is the answer.