Here's a short story: The iRobot cleans the tiles faster than the plush carpet because it has (A) more friction (B) less friction. What is the most sensical answer between "tiles" and "plush carpet"?
plush carpet

Here's a short story: The torpedo soared through the air quicker than through sand because it has (A) less friction (B) more friction. What is the most sensical answer between "air" and "sand"?
air

Here's a short story: Penny rode her bicycle quickly on the pavement and had to go slow through the thick mud because it had (A) more resistance (B) less resistance. What is the most sensical answer between "pavement" and "thick mud"?
pavement