Answer:
Answer is Option A: They acted as gateways to gold-rush regions.
Explanation:
The Alaska's gold rush played a significant role in the economic growth of countries like Seattle and Portland. This led to economic dominance of these countries among Northwest cities.
The California's gold rush brought a sudden and large growing market for timber. That is when Seattle then got its first profits in trade of crushed or milled timber south to the Bay Area and the Sierra goldfields. It became the center for trade and the gold rush came to include Alaska. Thousands of men and women, who passed through Seattle on their way to the Klondike and Alaska and each industry of that region obtained a boost. Seattle merchants sold meat, dried fruit, and flour to the miners. They also sold clothing and equipment.
As Seattle "captured" the Alaska trade, it solidified the economic growth and ties between the city and Alaska grew stronger.