1. For how many real numbers $x$ does the chain of inequalities $0 \leq x \leq \frac{1}{x} \leq 1$ hold?
(A) infinitely many
(B) 3
(C) none
(D) only 1
(E) 2
(1) The correct answer is $(D)$.

The only solution is clearly $x=1$, since, if it were $01$.

Question proposed by Sandro Campigotto.