Which of the following statements about iodometric and iodimetric titrations are correct?

1. AExcess $\mathrm{KI}$ keeps the liberated $\mathrm{I}{}_2$ dissolved as $\mathrm{I}{}_3{}^{-}$ and reduces its volatility.
2. BIn iodometry an oxidising agent liberates iodine from excess $\mathrm{KI}$ and the iodine is titrated with thiosulphate.
3. CIn iodometry the starch indicator should be added at the very beginning, when iodine concentration is highest.
4. DIn iodimetry a standard iodine solution is used directly to titrate a reducing agent.