How could it have had a zero real rate of return? $($Select the best answer below.$)$

A$.$ The real return would be zero if the T$-$bill rate was greater than the CPI rate.

B$.$ The real return would be zero if the T$-$bill rate was less than the CPI rate.

C$.$ The real return cannot be zero.

D$.$ The real return would be

$-$o if the $T-$bill rate was $3\mathrm{.}3\%,$ exactly matching the $\frac{C}{P}$I rate,