39. Compare the advantages and limitations of microarrays and Northern blots for analyzing gene expression. Which statement listed below is correct? 　 1. Microarrays allow a more global analysis of gene expression by analyzing thousands 　 2. Microarrays data analysis can reveal groups of known and unknown genes that are regulated in a coordinated fashion. 　 3. Northern blots allow the analysis of only a few genes at a time. 　 4. Northern blot can reveal the presence of multiple mRNAs from one gene locus that may be differentially expressed. The presence of multiple mRNAs could be missed by microarray analysis. (A) 1, 2, 3 are correct. (B) 1, 3, 4 are correct. (C) 2, 3, 4 are correct. (D) 1, 2, 4 are correct. (E) All of above are correct.