The next time you get caught jumping on your bed you can tell your parents with a straight face that you are not playing, simply getting ready got a promising career in "Mattress Jumping". Believe it or not, there are some people who actually get paid to do that! According to Reuben Reynoso, a professional mattress tester at San Francisco's McRoskey Mattress Factory that still makes every mattress by hand, it is real work and needs some training. For a start, it's not all about jumping to new heights or doing tricks like professional athletes, but rather about feeling each area of the mattress carefully to detect the filling. In order to do it right, every bit of the mattress has to be tested slowly and deliberately. Over the years, Reynoso has figured out the perfect routine. He begins by placing a protective mat over the mattress so that it doesn't get dirty or absorb the smell from his feet. Then begins the fun---he steps to the middle of an edge and then takes five steps back and five steps forward. In this way, he slowly but surely, covers the entire surface. The key according to him is to find the perfect number of jumps---Too many and he will end up destroying the mattress completely. Too few? And it will not fit into the giant machine for that final sewing! Who knew a job that sounds so simple could have so many skills! While Reuben will not reveal how he got into this profession, he will admit that it is more fun than being a carpenter, roofer, construction worker and railroad engineer---all jobs he has tried previous to finding his true profession! According to Reynoso, the most important thing in his work is   _  .
the timing of his jumps the height of his jumps the number of his jumps the frequency of his jumps