The rare earth elements that are considered extremely important for widely used modern technologies include
a. scandium and yttrium
b. scandium, yttrium and the 15 lanthanides
c. yttrium, cobalt and the 15 lanthanides
d. scandium, nobelium and the 15 lanthanides
e. the 17 lanthanides alone
B
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A. Autotrophs B. Heterotrophs C. Chemoautotrophs D. Photosynthotrophs
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