Question

read this sentence from the evolution of useful things. making waterproof sandpaper would allow wet sanding, which in turn would cut down on dust, and thus be a great improvement. the underlined phrases indicate
passing of time.

a directional change of position.

a cause - and - effect relationship.

sequence of events.

Explanation:

• "Which in turn" and "and thus" are transition phrases.
• They show that making waterproof sandpaper (cause) leads to wet sanding, which then leads to less dust (effect), and finally to an improvement (another effect).

Answer:

a cause - and - effect relationship.