Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

[Q]: Five or six years ago, I attended a lecture on the science of attention. A professor who conducts research over in the medical school was talking about attention blindness, the basic feature of the human brain that, when we concentrate on one task, causes us to miss just about everything else. Because we can't see what we can't see, our lecturer was determined to catch us in the act. He had us watch a video of six people tossing basketballs back and forth, three in white shirts and three in black, and our task was to keep track only of the tosses among the people in white. The tape rolled, and everyone began counting. Everyone except me. I'm dyslexic , and the moment I saw that tape with the confusing basketball tossers, I knew I wouldn't be able to keep track of their movements, so I let my mind wander. I became curious, though, when about 30 seconds into the tape, a gorilla walked in among the players. She (we later learned a female student was in the gorilla suit) stared at the camera, beat her chest with her fist, and then went away while they continued passing the balls. When the tape stopped, the professor asked how many people had counted at least a dozen basketball tosses. Hands went up all over. He then asked who had counted 13, 14, and congratulated those who'd scored the perfect 15. Then he asked, "And who saw the gorilla?" I raised my hand and was surprised to discover I was the only person at my table and one of only three or four in the large room to do so. He'd set us up, trapping us in our own attention blindness. Yes, there had been a trick, but he wasn't the one who had played it on us. By concentrating so hard on counting, we had managed to miss the gorilla in the midst. Attention blindness is the fundamental organizing principle of the brain, and I believe that it presents us with a great opportunity. My take is different from that of many neuroscientists: Where they see the shortcomings of the individual, I sense an opportunity for cooperation. Fortunately, given the interactive nature of most of our lives in the digital age, we have the tools to control our different forms of attention and take advantage of them. It's not easy to admit that everything we've learned about how to pay attention means that we've been missing everything else. It's not easy for us logical, intelligent, confident types to admit that the very key to our success -- our ability to discover a problem and solve it, an achievement obtained in all those years in school and beyond -- may be exactly what limits us. No one ever told us that our way of seeing left out everything else.
[A]: What's the total number of basketball tosses by the players in white shirts in the video?


[Q]: Polycomb gene silencing requires histone methyltransferase activity of Polycomb repressive complex 2 (PRC2), which methylates lysine 27 of histone H3. Information on how PRC2 works is limited by lack of structural data on the catalytic subunit, Enhancer of zeste (E(Z)), and the paucity of E(z) mutant alleles that alter its SET domain. Here we analyze missense alleles of Drosophila E(z), selected for molecular study because of their dominant genetic effects. Four missense alleles identify key E(Z) SET domain residues, and a fifth is located in the adjacent CXC domain. Analysis of mutant PRC2 complexes in vitro, and H3-K27 methylation in vivo, shows that each SET domain mutation disrupts PRC2 histone methyltransferase. Based on known SET domain structures, the mutations likely affect either the lysine-substrate binding pocket, the binding site for the adenosylmethionine methyl donor, or a critical tyrosine predicted to interact with the substrate lysine epsilon-amino group. In contrast, the CXC mutant retains catalytic activity, Lys-27 specificity, and trimethylation capacity. Deletion analysis also reveals a functional requirement for a conserved E(Z) domain N-terminal to CXC and SET. These results identify critical SET domain residues needed for PRC2 enzyme function, and they also emphasize functional inputs from outside the SET domain.
[A]: What is the characteristic domain of histone methyltransferases?


[Q]: Producing money requires both artistic and technological skills. Dollar bills are made so that they are interesting to look at but very hard to copy. In total, there are sixty-five separate steps required to make a dollar bill. The money making process begins when. a yearly order is sent by the Federal Reserve Board. That order will then be divided in half. Half will be done here in Washington, D. C.and the other half will be done in Fort Worth, Texas. Next, the Bureau orders special paper which is actually cloth since it is 75% cotton and 25% linen. This paper is made so that it can last a long time. And, it is made with details that make it hard to copy. For example, bills contain security threads. These narrow pieces of plastic are inside the paper and run along the width of the bill. This special paper is also made with very small blue and red fibers. Once the money is printed, guillotine cutters separate the sheets into two notes, then into individual notes. The notes are organized in "bricks," each of which contains forty one-hundred-note packages. The bricks then go to one of twelve Federal Reserve Districts, which then give the money to local banks. Ninety-five percent of the bills printed each year are used to replace money that is in circulation, or that has already been removed from circulation. You may know that America's first president, George Washington, is pictured on the one- dollar bill. But do you know whose face is on the two, five, ten, twenty, fifty and one hundred-dollar bills? They are, in order. President Thomas Jefferson, President Abraham Lincoln, Treasury Secretary Alexander Hamilton, President Andrew Jackson, President Ulysses Grant and statesman Benjamin Franklin. The average life span of a one-dollar bill is twenty-one months. But a ten-dollar bill lasts only about eighteen months. The one hundred-dollar bill lasts the longest, eighty-nine months. One popular question is about the two-dollar bill. This bill is not printed very often. This is because many Americans believe two-dollar bills are lucky, so they keep them.
[A]:
How many presidents are printed on the American money?