Which statement is true about time signatures? a)The top number indicates the number of beats per measure, while the bottom number indicates what note equals one beat b) The top number indicates what note equals one beat, while the bottom number indicates the number of beats per measure c) The top number indicates how many notes can be in a measure, while the bottom number indicates how many measures can be in one line. d) Time signatures define how fast or slow a musical piece should be played.​