CONCEPT:Angstrom: The UNIT of length which is equal to 10−10 meters is CALLED one Angstrom.Angstrom is DENOTED by Å.1 Å = 10-10 mEXPLANATION:Angstrom is a unit of length. So option 3 is correct.EXTRA POINTS:SI PrefixPrefixSymbolMultiplierexaE1018petaP1015teraT1012gigaG109megaM106kilok103hectoh102decada101decid10-1centic10-2milim10-3microμ10-6nanon10-9angstromÅ10-10picop10-12femtof10-15attoa10-18