Question: What genre of music  did Loudest Whisper debut on a vinyl record format characterized by a speed of 33 ⁄ rpm, a 12 or 10 inch (30 or 25 cm) diameter, and use of the "microgroove" groove specification?
Sentence (from "List of number-one EPs in the United Kingdom"): EPs "died out in the late 1960s" and "Record Retailer" reduced the chart to ten positions on 16 April 1966, publishing the final EP chart on 16 December 1967.
Relevant evidence: No