Which of the following is an aerobic activity bicycling fishing or racing your sister to the telephone?

Bicycling would be the only sustained aerobic activity.

Of course, if you were racing your sister to a telephone a couple of miles away, or you had to fight a legendary fish for an hour, those *could* also be sustained aerobic activities. :)

By the same token, if you just rode your bike to the driveway and back, it wouldn't help much either.