Going slower than traffic’s flow is often better

Q. I am due to renew my license soon and am confused about the one answer I got wrong on the Department of Motor Vehicle’s practice tests: You are driving on a freeway posted for 65 mph, with traffic traveling at 70 mph – how fast should you drive? The correct answer was listed as: “No faster than 65 mph.” I have always thought the so-called Basic Speed Law meant that one should maintain a speed on the freeway that keeps with the flow, rather than going slower than other