A number of linguists contend that all of the thousands of languages spoken by
the world's five billion people can be traced back to a common root language.

(A) that all of the thousands of languages spoken by the world's five billion
people can be traced
(B) that the world's five billion people speak thousands of languages of which all
can be traced
(C) the world's five billion people speak thousands of languages which are all
traceable
(D) all of the thousands of languages spoken by the world's five billion people to
be traceable
(E) the ability to trace all of the thousands of languages that are spoken by the
world's five billion people

IMO (A)

OA not provided