20. What header file must be included A) to perform mathematical functions like sqrt? B) to use files? C) to use stream manipluators like setprecision? Print Layout View Sec 1 Pages: 7 of 7 Words: 1999 of 1999 11 F2 80 F3 000 goo F4 F5 F6 F7 % 95 54 #3 LL E D 96 27 & * 8