The diagram illustrates an experiment. At the beginning of the experiment, a starch suspension is white and iodine solution is yellow/brown. After $6$ hours, the starch suspension is blue/black. Why has the starch suspension changed colour?
- AIodine has diffused in through the membrane.
- BIodine has diffused out through the membrane.
- CStarch has diffused in through the membrane.
- DStarch has diffused out through the membrane.