You want to find out which of the consequent gene X or Y is being transcribed. For this you do a hybridization competition analysis and plot the radioactivity curve with increasing concentration of the competitor unlabelled mRNA. If the transcribed gene was X, which observation fits your result?

Correct Answer: The radioactivity of x decreases while that of y remains the same
As the unlabelled mRNA against X will compete with the labeled one for hybridization the intensity of radioactivity will gradually decrease with increased concentration. But as it will not bind to Y gene the Y labeled mRNA faces no competition and its intensity remains same.