Question

which discovery is attributed to phoebus levene?
extraction and observation of dna
identification of ribose and deoxyribose
recognition of rna as dnas messenger
construction of an accurate dna model

Explanation:

Phoebus Levene is known for his work in nucleic acids. He identified ribose (in RNA) and deoxyribose (in DNA). Extraction and observation of DNA was done by Johann Friedrich Miescher. The recognition of RNA as DNA's messenger was part of later work in molecular biology (not specifically Levene's main discovery). The construction of an accurate DNA model was by Watson and Crick.

Answer:

identification of ribose and deoxyribose