Final answer:
Syncopation in music involves altering the rhythm and emphasizing offbeats. Accenting an offbeat and using a syncopated bassline are examples of syncopating music. Playing a straight quarter-note rhythm is not a method of syncopating music.
Step-by-step explanation:
Syncopation is a method of altering the rhythm of music by accenting the offbeat, which means emphasizing beats that are not typically emphasized. So, statement a) Accenting an offbeat is an example of syncopating music. Playing a straight quarter-note rhythm, as mentioned in statement b), is not a method of syncopating music because it does not involve changing the rhythm or emphasizing offbeats. Tying two eighth notes across a beat, mentioned in statement c), does involve altering the rhythm, so it is an example of syncopation. Lastly, using a syncopated bassline, as mentioned in statement d), is another example of syncopating music because it changes the rhythm by emphasizing offbeats.