The Yo-Yo in America
Contrary to popular belief, the yo-yo is not an American invention. A
woung man from the Philippines named Pedro Flores is believed to have
introduced the toy to American audiences when he moved here in the
920s. He had carved and played with yo-yo's in his native Philippines,
as it was a traditional pastime there. When Pedro played with the toy on
this lunch break at a Santa Monica, California, hotel where he worked as
a bellhop, he found that it drew a crowd of curious onlockers. So he
started a company-the Flores Yo-Yo Company-and began
manufacturing the toys.
In 1928, a businessman named Donald Duncan saw yo-yo's for the
first time when he was on a business trip to Califomia. He had a hunch
the toy would be a goldmine, so a year later, he came back and
purchased the company from Flores. Duncan was quite an innovator.
and he immediately set about improving on the design. He soon
introduced a special string called a looped slip-string With this string, the
loop at one end goes around the axle of the yo-yo. This means the yo-yo
is allowed to sleep during a trick In other words, when the yo-yo is
thrown down to start a trick, it will spin at the bottom of the string for a
minute or so, until the player tugs it back up again. This type of string
opened the door for all the fancy advanced tricks to come
In the 1950s, Duncan began making plastic yo-yos, which were
cheaper to make and lighter to play with than the wooden ones. He also
made the first Butterfly yo-yo's, shaped like their name. The wing-like
sides made it easy for the player to land the yo-yo right on the string
when doing difficult tricks. By the late 1950s and early 1960s, TV
advertising had reached households all across America, causing the
biggest yo-yo boom in history in 1962. Sales skyrocketed. Unfortunately,
the company lost money when the boom ended. Duncan also had to fight
an expensive lawsuit to protect the yo-yo trademark from competing
companies. Duncan went out of business in the late 1960s, and a
company called Flambeau Products took it over. Even so, in many
people's minds, the name of Duncan will always be synonymous with the
The term boom means what in the passage?
CA a very loud sales day
OB a tremendous drop in sales
CC. a slow, steady improvement
OD. a sudden increase in popularity

I don’t understand