Which of the following best describes a required convention when drawing a free-body diagram for a single object?
a) Internal forces within the object should be drawn if they are significant.
b) Each external force must be represented by an arrow that originates at a single dot representing the object.
c) Vector components of a single force should be drawn as separate arrows on the diagram.
d) Only the forces that make the object accelerate need to be included; forces that balance can be omitted.