Question

the newcomen ______ one of the world’s first functional steam engines—used steam to create a vacuum that utilized atmospheric pressure to force a piston downward, moving in cycles of about twelve pumps per minute.

which choice completes the text so that it conforms to the conventions of standard english?

choose 1 answer:

a engine

b engine—

c engine,

d engine;

Explanation:

The text uses an em dash after "engines" to set off a descriptive clause about the Newcomen engine. To correctly introduce this parenthetical information, we need to pair the closing em dash with an opening em dash after the noun phrase "The Newcomen engine". This creates a grammatically correct, standard English structure for setting off explanatory content.

Answer:

B. engine—