Answer:
The correct answer is - It shows that an RNA probe is necessary to get a signal.
Explanation:
A probe is a specific single-stranded sequence of DNA or RNA that recognizes its complementary sequence in a particular sample genome for synthesis. The RNA probe is placed into close contact with the given sample under a specific environment that allows the RNA probe sequence to hybridize with its complementary sequence.
In this case, square a is the condition where no RNA probe is persent whereas all three other conditions have some sort of RNA probe, however, in C there is no Gene X probe but their probe present. To get a signal in hybridization RNA probe is required and that can be used as control as it can be used to compare if a signal is received or not.
