Which element of musical notation does this image represent? a. sharp sign b. flat sign c. natural sign d. ledger lines

sharp sign. flats look like little (b)s, like this, ♭, naturals look like a a rectangle with one line coming out of the top and one from the bottom, ♮, and ledger lines are a short line added for notes above or below the range of a staff. basically, lines where there is supposed to be a staff's line, but it's on the blank space on top or on the bottom, to show you there is supposed to be one there. (see picture attached)

eugene boudin greatly inspired claude monet's art.