根据短文内容，从短文后的选项中选出能填入空白处的最佳答案。选项中有两个为多余选项。
Millions of people all over the world use the word OK. In fact, some people say the word. OK means all right or acceptable it expresses agreement or approval.
___1___ .Some people say it came from the Native American Indian tribe known as the Choctaw. The Choctaw word “oken” means the same as the American word “okay”. Experts say early explorers in the American West spoke the Choctaw language in the 19th century.
But many people doubt this. Language expert Allen Walker Read wrote about the word OK in reports published in the 1960s. He said the word began being used in the 1830s. ___2___.Some foreign –born people wrote “all correct” as  “o-l-l k-o-r-r-e-c-t”, and used the letters O.K. Other people say a railroad worker named Obadiah Kelly invented the word long ago. They said he put the first letters of his names--- O and K --- on each object people gave him to send on the train.
__3__ The organization supported Martin Van  Buren for president in 1840. They called their group the OK Club. The letters were taken from the name of the town where Martin Van Buren was born--- Old Kinderhook, New York.
Then there is the expression A-OK. It is a space-age expression. It was used in 1961 during the flight of astronaut Alan Shepard. He was the first American to be launched into space. His flight ended when his spacecraft landed in the ocean, as planned. Shepard reported, “Everything is A-OK.”__4__ One story says it was first used during the early days of the telephone to tell an operator that a messa ge had been received.
There are also funny ways to say okay. __5__ .These expressions were first used in the 1930s. Today, a character on the American television series, “The Simpsons”, says it another way. He says okely-dokely.

A．Some people say okey-dokey or okey-doke.

B．Still others say a political organization invented the word.

C．Therefore, it has become popular in that area from then on.

D．But many experts don’t agree on what the expression means.

E. Language experts do not agree about where the word came from.
F. It was a short way of writing a different spelling of the words “all correct”.
G. However, some exerts say the expression did not begin with the space age.