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

Q: In plant, primary transcripts (pri-miRNAs) transcribed from miRNA genes by RNA polymerase II are first processed into stem-loop pre-miRNAs and further chopped into 21nt long miRNAs by RNase III-like enzyme DCL1. SERRATE (SE) protein is an essential component for miRNA processing by assisting DCL1 for accurate cleavage. Here we report the crystal structure of Arabidopsis SE core (residues 194-543) at 2.7A. SE core adopts the 'walking man-like' topology with N-terminal helices, C-terminal non-canonical zinc-finger domain and novel Middle domain resembling the leading leg, the lagging leg and the body, respectively. Pull-down assay shows that SE core provides the platform for HYL1 and DCL1 binding, whereas in vitro RNA binding and in vivo mutant rescue experiments suggest that the non-canonical zinc-finger domain coupled with C-terminal tail binds miRNA precursors. SE presumably works as a scaffold-like protein capable of binding both protein and RNA to guide the positioning of miRNA precursor toward DCL1 catalytic site within miRNA processing machinery in plant.

A: Which polymerase transcribes pri-miRNAs?
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Q: In 1997 the Kymi Province was merged with the Uusimaa Province and the southern parts of the Hame Province into the new Southern Finland Province.

A: What was replaced Kymi Province?
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Q: There are 27,908 households, of which 31.5% have children under the age of 18 living with them, 48.9% were married couples living together, 15.4% had a female householder with no husband present, and 32.3% were non-families. 28.4% of all households are made up of individuals, and 10.6% had someone living alone who was 65 years of age or older. The average household size was 2.39, and the average family size was 2.94. 70% of women with school-age children work.

A:
which household was fourth most common?
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