Which experimental design would best utilize cDNA libraries to study gene expression changes due to temperature shifts?

Use restriction enzymes to cut mRNA, insert into vectors, sequence to identify expressed genes.

Expose cells to different temperatures, isolate mRNA, create cDNA libraries, sequence to identify expressed genes.

Expose cells to different temperatures, isolate genomic DNA, create genomic libraries, sequence to identify expressed genes.

Expose cells to different temperatures, isolate proteins, create cDNA libraries, sequence to identify expressed genes.