Which of the following type of Human Herpesvirus causes Kaposi's sarcoma?

HHV 8 is the causative agent of Kaposi's sarcoma. Kaposi's sarcoma is a spindle cell tumor derived from endothelial cell lineage. It is characterised by the presence of cutaneous lesions mostly on the lower extremities and in the head and neck regions. The lesions may be macular, papular, nodular or plaque like with colors varying from brown to pink to red or violaceous. HHV 6 is the causative agent of Roseola infantum. It usually affects children aged 6 months to 2 years. Patients present with high fever, which drops on the fouh day coinciding with the onset of a rash with characteristic 2-5mm pink macules that begins in the trunk and may spread to neck and upper and lower extremities. On examination they have bulging anterior fontanelle, tonsillar and pharyngeal inflammation, tympanic injection and lymph node enlargement. Ref: Skin Infections: Diagnosis and Treatment edited by John C. Hall, page 33.