Answer:
Every action has a reaction, therefor the marble will first be affected by air resistance, and also friction when the gravitational pull will cause it to drop to the ground. Eventually, the marble will have to come to a stop. If this marble was thrown in space, the marble will continue on in a horizontal line at a constant speed of 15 m/s, and this is because there is no air resistance acting against the marble, as well as no friction.
