Fossils older than ____ cannot be dated by their 14C content because ____
a. 60,000 years; most of the 14C has decayed by this time
b. 12,000 years; half of the 14C has decayed by this time
c. 6,000 years; older fossils do not contain carbon
d. 2,000 years; most of the 14C has decayed by this time
e. 500 years; half of the 14C has decayed by this time
ANSWER: a
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Fill in the blank(s) with the appropriate word(s).
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