The correct answer is: Short phrases that make the reader interested.
Some authors recommend the use of short sentences as the genre requires variety and flow to avoid repetition and boredom. In this way the pace of the reading is increased keeping the reader's attention. I read an example that was very helpful, imagine someone that is anxious or scared, when he sepaks he uses few words at a time, forming complex sentences turns difficult. By writing with short sentences you can be able to transmit this kind of emotions in a more effective way. Remember that suspense's objective is to make the reader wonder at all time if the protagonist will overcome the problems presented, the reader must frecuently face uncertainty.