In the Binomial Model,if the Stock Moves Up by a Factor

Multiple Choice

In the binomial model,if the stock moves up by a factor $\mathcal { U }$ and down by a factor $d$ ,and a $1 investment in a risk-free bond returns an amount $R$ per time step,which of the following statements is true in a market that is free from arbitrage?

A) $d < u < R$
B) $u < R < d$
C) $d < R < U$
D) $R < d < u$