3 HIGH Cs: These three sopranos with the Naturecoast Singers will present a take-off on the popular Three Tenors at 3 and 7 p.m. Saturday. In their debut performance, each will perform three or four familiar arias to showcase the composers' talents and the singer's mastery. The program will feature a duet, trio and a piano solo by their accompanist, Vladimir Khokhov, a graduate of the Leningrad Conservatory. The program is sponsored by Mariner United Methodist Church Community Performing Arts Guild, 7079 Mariner Blvd., Spring Hill. Free tickets still are available. Call 596-0080 or visit the church office.