Final answer:
Competition increases the likelihood of new firms entering the market, which elevates pressure on existing firms to enhance their efficiency. In decreasing cost industries, expansion leads to lower production costs and prices, often due to technological advances or better-educated workers.
Step-by-step explanation:
Related industries create the probability that new companies will enter the market. This competition increases and forces existing firms to improve efficiency. The correct completion of the sentence is: increases; existing; efficiency. When competition arises from firms with better or cheaper products, it can lead to a reduction in a business's profits, and possibly drive it out of the market. This heightens the risk for workers to lose income or their jobs. However, for a decreasing cost industry, as the market expands, both old and new firms experience lower costs of production, which leads to lower prices and higher efficiency. This drop in average total costs could be attributed to advancements in technology or improvements in employee education, especially in high-tech industries.