They are descended from wild plants.
Answer:
The correct answer is option a, that is, the thrM and thrN would be transcribed at high levels in comparison to non-mutant.
Explanation:
Based on the given information, in the existence of thorain the expression of thrM and thrN will be prevented as thorain functions as a negative regulator. In case, if the gene, which codes for thorain, that is, thrL gets mutated, the coding for the functional thorain would get prevented.
With the encoding of the non-functional thrL protein, there would be an enhancement in the expression of thrN and thrM genes and it will get transcribed at higher levels in comparison to the non-mutant or the wild-type.
