Which of the following most logically completes the argument?
Although the pesticide TDX has been widely used by fruit growers since the early 1960s, a regulation in force
since 1960 has prohibited sale of fruit on which any TDX residue can be detected. That regulation is about to be
replaced by one that allows sale of fruit on which trace amounts of TDX residue are detected. In fact, however,
the change will not allow more TDX on fruit than was allowed in the 1960s, because .
(A) pre-1970 techniques for detecting TDX residue could detect it only when it was present on fruit in more
than the trace amounts allowed by the new regulations
(B) many more people today than in the 1960s habitually purchase and eat fruit without making an effort to
clean residues off the fruit
(C) people today do not individually consume any more pieces of fruit, on average, than did the people in the
1960s
(D) at least a small fraction of the fruit sold each year since the early 1960s has had on it greater levels of
TDX than the regulation allows
(E) the presence of TDX on fruit in greater than trace amounts has not been shown to cause any harm even to children
who eat large amounts of fruit

I don't know why OA is A