29. Which of the following sequences is NOT found in pre-mRNA? (A) Exon (B) Intron (C) Promoter (D) Stop Codon

5. Which of the following statements is INCORRECT for retroviruses? (A) They are enveloped RNA virus. (B) They encode reverse transcriptase and replicate through a DNA intermediate. (C) Some of them produce tumors in the infected animals. (D) Retroviruses include human immunodeficiency virus (HIV) which primarily infects CD8 T cells.