Final answer:
RNA can indeed hold genetic information, but due to its instability, it is generally not used for long-term storage of genetic information in most current living organisms. The primary reason it isn't considered a storage molecule is because of its relatively short-lived nature compared to DNA.
Step-by-step explanation:
The student asked about the capabilities of RNA in storing genetic information. It is not entirely accurate to say that RNA cannot store genetic information at all; rather, the reality is more nuanced. The statement "RNA lacks the necessary structure to store genetic information" is not correct, as RNA can hold genetic information but is usually involved in different roles within the cell.
The assertion that RNA is unstable and cannot maintain genetic information over time is more to the point, as RNA's instability compared to DNA makes it less suitable for long-term storage of genetic information. Furthermore, saying that RNA is only involved in protein synthesis, not storage, is a simplification, as RNA can also have regulatory roles and some viruses do use RNA as their genetic material. The claim that RNA is unable to replicate itself is misleading, as certain types of RNA can undergo self-replication, though this is not a common function of RNA in most living cells today.
In summary, while RNA can encode and carry genetic information, particularly in some viruses and in early forms of life according to the RNA world hypothesis, it is typically not used to store genetic information in most current living organisms due to its relative instability and because it is primarily involved in protein synthesis. Therefore, the most accurate answer to the student's question would be 2) RNA is unstable and cannot maintain genetic information over time, though with the understanding that there are exceptions under certain circumstances.