Dental caries is caused by-

Ans. is 'b' i.e., Streptococcus mutans o Streptococcus mutans belongs to viridans streptococci and is an important cause of dental cariesMedically important streptococci and their characteristicsSpecies or common nameLancefield groupHemolysisHabitat in human hostsLaboratory testCommon diseases causedStr. PyogenesAbetaThroat, skinBacitracin sensitive; PYR test positive; Ribose not fermentedUpper respiratory tract infection; pyoderma; rheumatic fever; glomerulonephritisStr. agalactiaeBbetaFemale genital tract, rectumCAMP test, hippurate hydrolysisNeonatal menigitis, septicemiaStr. equisimilisCbetaThroatRibose and trehalose fermentationPharyngitis,endocarditisStr. cinginosusA,C,F,G untypablebeta (alpha, gamma)Throat colon female genital tractGroup A strains bacitracin resistant PYR negative; Minute colony variants of other groupsPyogenic infectionsEnterococcus sp. (Str. faecalis and other enterococci)DGamma (alpha, beta)ColonGrowth in 6.5% NaCI; PYR positive Urinary tract infections, endocarditis, Nonenterococcal Group D species (Str. bovis)DGammaColonNo growth in 6.5% NaCISuppurative infections EndocarditisViridanssteptococci (many species)No typedalpha(gamma)Mouth colon, female genital tractOptochin resistant Species classification on biochemical propertiesEndocarditis (Str. saneuis); dental caries (Str. mutans)