Shelby is organizing information for a report about an American fitness expert named Jack LaLanne. Which sentence fits best in the box containing the question mark?

Incomplete question. Answered based on available information.

The missing options read;

A. Handcuffed, Jack swam from Alcatraz to Fisherman's Wharf in San Francisco in 1955.

B. Jack LaLanne received a star on the Hollywood Walk of Fame in 2002.

C. In 1954, Jack set a world record by swimming the length of the Golden Gate Bridge.

D. In 1950, Jack started inventing many of the first exercise machines.

D. In 1950, Jack started inventing many of the first exercise machines.

Explanation:

In the English language, one of the main use of the question mark symbol is to solicit or make a query about a particular action, subject or thing.

In the sentences above, we notice that saying, "In 1950, Jack started inventing many of the first exercise machines" best fits the box containing the question mark.