Final answer:
Sliding friction is involved when leaving marks on paper with a pencil 'lead'.
Step-by-step explanation:
The type of friction that is involved when leaving marks on paper with a pencil 'lead' is sliding friction. Sliding friction occurs when two surfaces slide against each other, and it is the force that allows the pencil to interact with the paper and leave marks. This type of friction is different from rolling friction, which occurs when an object rolls over a surface, and fluid friction, which occurs when an object moves through a fluid.
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