The teacher of yoga said that he knows how good the yoga exercises feel and how beneficial

The teacher of yoga said that he knows how good the yoga exercises feel and how beneficial they are to his mental and spiritual health. After all, he said, there must be something sound to any human practice that endures more than three thousand years of history. Which of the following, if true, is the strongest relevant objection to the argument the teacher makes on the basis of the time yoga has endured？

A．The teacher benefits by the teaching of yoga and so, as a beneficiary, is not a disinterested witness.

B．The practice of yoga has changed somewhat over three thousand years.

C．The teacher cites the experience of only one person, whose well-being might be due to other causes.

D．War, which cannot on balance be called sound, has lasted the length of human history.

E．Three thousand years is an underestimate of the time period.

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