In the shallow end of Lake Tomwa, there are remains of numerous Jeffery pine trees that grew there
during a lengthy drought. Researchers had believed that this drought lasted at least 150 years, but carbon
dating reveals that pines were growing in the lake bed for only 120 years, from 1200 until 1320. Since the
Jeffrey pines, which cannot survive in water, must have died at the end of the drought, the dating shows that
the drought lasted less than 150 years.
The argument given relies on which of the following as an assumption?
ⓐ No other species of tree started growing in the bed of Lake Tomwa after 1200.
ⓑ No tree remains of any kind are present at the bottom of deeper parts of Lake Tomwa.
ⓒ There was at least one tree in the lake bed that was alive for the entire period from 1200 to 1320.
ⓓ There has not been a more recent drought that caused a drying up of the shallow end of the lake.
ⓔ The shallow end of the lake had been dry for less than 30 years by the time Jeffrey pines started growing in
the lake bed.
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