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

Example Input: ''Wolves Beyond the Border'' is one of the original stories by Robert E. Howard about Conan the Cimmerian, a fragment begun in the 1930s but not finished or published in Howard's lifetime.
Example Output: Who was Wolves Beyond the Border written by?

Example Input: The SWR1 complex (SWR1C) in yeast catalyzes the replacement of nucleosomal H2A with the H2AZ variant, which ensures full activation of underlying genes. We compared the phenotype of mutants in the homologs of SWR1C components in Arabidopsis thaliana. Mutations in Arabidopsis SWC6 (AtSWC6), SUPPRESSOR OF FRIGIDA 3 (SUF3) and PHOTOPERIOD-INDEPENDENT EARLY FLOWERING 1 (PIE1), homologs of SWC6, ARP6 and SWR1, respectively, caused similar developmental defects, including leaf serration, weak apical dominance, flowers with extra petals and early flowering by reduction in expression of FLOWERING LOCUS C (FLC), a strong floral repressor. Chromatin immunoprecipitation assays showed that AtSWC6 and SUF3 bind to the proximal region of the FLC promoter, and protoplast transfection assays showed that AtSWC6 colocalizes with SUF3. Protein interaction analyses suggested the formation of a complex between PIE1, SUF3, AtSWC6 and AtSWC2. In addition, H2AZ, a substrate of SWR1C, interacts with both PIE1 and AtSWC2. Finally, knockdown of the H2AZ genes by RNA interference or artificial microRNA caused a phenotype similar to that of atswc6 or suf3. Our results strongly support the presence of an SWR1C-like complex in Arabidopsis that ensures proper development, including floral repression through full activation of FLC.
Example Output: Which protein mediates the replacement of H2A by H2A.Z in the yeast Saccharomyces cerevisiae?

Example Input: The Act of Union 1840, passed July 23, 1840 by the British Parliament and proclaimed by the Crown on February 10, 1841, merged Upper Canada with Lower Canada to form the short-lived United Province of Canada.
Example Output:
What was replaced Upper Canada?