In the case of microarrays ____________

A.  Often the whole organism is not sequenced

B. Changes in transcript level can be studied in response to environmental changes

C. RNA is synthesized only after the property which is to be studied is inculcated

D. DNA is synthesized for this RNA by transcriptase

Explanation: In microarrays, often the whole organism is sequenced on the solid support such as a slide. The change in the transcript level can be studied in response to environmental changes. The RNA is synthesized both for before and after the change is to be studied. DNA is synthesized for both RNAs by reverse transcriptase.