In order for medicine X to produce the effects that the researchers observed it must have entered into which part of the target cells

golgi apparatus

rough endoplasmic reticulum

nucleus

ribosomes

The correct option is option C, nucleus

Explanation:

As the scenario described in the question, the medicine X functions on the DNA as it's characteristic shows that it is damaging the DNA. The DNA is present inside the nucleus of a cell. Hence, for a medicine to function on the DNA, the medicine must enter the nucleus of the cell as it is the location where the DNA is present.

Other options like, option D, is not correct because the process of conversion of mRNA into proteins takes place in the ribosomes and DNA is not present there.