Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Example Input: Context: In 2000, the label moved from Brussels to London and was renamed PIAS Recordings. 
 Question: What city is the band PIAS Recordings from?
Example Output: brussels

Example Input: Context: Ca2+ is a ubiquitous intracellular messenger responsible for controlling numerous cellular processes including fertilization, mitosis, neuronal transmission, contraction and relaxation of muscles, gene transcription, and cell death. At rest, the cytoplasmic Ca2+ concentration [Ca2+]i is approximately 100 nM, but this level rises to 500-1,000 nM upon activation. In osteoblasts, the elevation of [Ca2+]i is a result of an increase in the release of Ca2+ from endoplasmic reticulum and/or extracellular Ca2+ influx through voltage gated Ca2+ channels. Many of the cellular effects of Ca2+ are mediated by the Ca2+ binding protein, calmodulin (CaM). Upon binding up to four calcium ions, CaM undergoes a conformational change, which enables it to bind to specific proteins eliciting a specific response. Calmodulin kinase II (CaMKII) is a major target of the Ca(2+)/CaM second messenger system. Once bound to Ca(2+)/CaM, the multimeric CaMKII is released from its autoinhibitory status and maximally activated, which then leads to an intraholoenzyme autophosphorylation reaction. Calcineurin (Cn) is another major target protein that is activated by Ca(2+)/CaM. Cn is a serine-threonine phosphatase that consists of a heterodimeric protein complex composed of a catalytic subunit (CnA) and a regulatory subunit (CnB). Upon activation, Cn directly binds to, and dephosphorylates nuclear factor of activated T cells (NFAT) transcription factors within the cytoplasm allowing them to translocate to the nucleus and participate in the regulation of gene expression. This review will examine the potential mechanisms by which calcium, CaM, CaMKII, and Cn/NFAT control osteoblast proliferation and differentiation. 
 Question: Which calcium/calmodulin dependent protein phosphatase is involved in the activation of the family of NFAT transcription factors (Nuclear Factors of Activated T cells)?
Example Output: can

Example Input: Context: One fine afternoon, I was walking along Fifth Street when I remembered that it was necessary to buy a pair of socks. Why I wished to buy only one pair was unimportant. I turned into the first sock shop that caught my eye. A boy clerk, who could not have been more than seventeen years old came forward. "What can I do for you, sir?" he said "I wish to buy a pair of socks." I replied. His eyes shone. There was a note of excitement in his voice. "Did you know that you had come into the finest place in the world to buy socks?" I had no idea of that, as my entrance had been accidental. "Come with me," said the boy, eagerly. I followed him to the back of the shop, and he began to pull down box after box from the shelves, showing their contents for my choice. "Hold on, lad" I said "I am going to buy only one pair!" "I know that," said he, "but I want you to see how beautiful these are. Aren't they wonderful!" There was on his face an expression of seriousness and pride and delight as if he were showing me the secrets of his religion . I became far more interested in him than in the socks. I looked at him in surprise. "My friend, " said I, "if you can keep this up, if this is not merely from having a new job, if you can keep up this high spirit and excitement day after day, in ten years you will own every sock in the United States." 
 Question: What did the writer want to buy one fine afternoon?
Example Output:
a pair of socks.