Researchers often want to isolate a certain type of RNA. For some RNA species, this can be accomplished via affinity chromatography, using beads coated with chains of poly-deoxythymidine (poly-dT). The desired RNA will stick to the beads while unwanted RNAs will flow through the column. The retained RNA can then be eluted. What RNA species can be purified using this method?

mRNA

Explanation:

poly-deoxythymidine (poly-dT) beads binds to polyadenylated (poly (A) molecules with high affinity because Thymidine base pairs with the Adenine of the poly(A) chain.

Since messenger RNA (mRNA) is polyadenylated after transcription in contrast to other RNA species, this method is more suitable for mRNA purification.

igneous rocks are formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.  

the composition depends on the source magma. there are almost a thousand types of composition found till now.  

hope this