Use the following paragraph to answer the next five questions.

in 1850 chicago was a tiny town on the outskirts of the northwest. but the steady advance of the railroad changed everything. chicago stood at the key junction between the railroads and ships that carried primary goods from the west and manufactured goods from the east. the population exploded as immigrants poured into the city, many of them staying rather than continuing farther west. until los angeles surpassed it in 1990, chicago ranked as the second largest city proper in the nation.

("the midwestern united states" in geography for christian schools by michael matthews)

choose the sentence with the correct use of ellipses.

a. "in 1850 chicago was a tiny town. . but the steady advance of the railroad changed everything."
b. "in 1850 chicago was a tiny town . . but the steady advance of the railroad changed everything."