Answer:
d. transition
Step-by-step explanation:
-Slide layout shows the design and formatting for everything you put in a slide.
-Video allows you to insert a video in the presentation.
-Animation allows you to put effects in the objects that you have in the presentation.
-Transition is the effect you can see in the presentation when you move from one slide to the other one and it helps you to control the speed.
According to this, the answer is that the presentation software element that you can use to control the speed between slides in a presentation is transition.