<prompt> All are true about streptococcus except :M-protein is responsible for production of mucoid coloniesM- protein is responsible for virulenceMucoid colonies are virulentNo resistance to penicillin has been reported  <response>: Mucoid colonies are due to production of capsule of hyaluronic acid not due to M protein.Harrison 17e, p 882Growth characteristic of Strep. pyogenes :On blood agar virulent stains forms matt or mucoid colonies while avirulent form glossy colonies.M, T, R are proteins found on outer part of cell wall and forms the basis of Griffith classification. M protein - Acts as virulence factor and antibody against it are protective. T and R protein - No relation to virulenceStreptococci Except enterococci are usually susceptible to penicillin so option d is not completely wrong. As option a is completely wrong, that would be the answer. 