The answer would be: <span>Binary fission involves a single parent cell, so there is only one set of genetic information that can be duplicated and passed on to the daughter cells.
If you see the picture, it is clear that there is only 1 parent involved in binary fission. This will exclude the first and third option.
The genetic duplicated before splitting, so the cells should have an equal number of parent genetic material, not halves. This will exclude the second option.
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First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is a catalyst. hope this helps :)