Answer:
Fossil B belongs to the same period as the trilobite.
Explanation:
The Law of Superposition states that the youngest rocks will always be found on top of older rocks. So as you dig deeper and deeper, the rocks you find will be older and older.
An illustration of the problem:
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Fossil C: Two Semi-circles (<u>Top</u> Layer = <em>Youngest</em>)
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Fossil B: Rhombus with Diagnonal & <em>Trilobite</em> (<u>Middle</u> Layer)
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Fossil A: Shaded Rhomboid (<u>Bottom</u> Layer = <em>Oldest</em>)
So, Fossil A is older than both B and C, or, B and C are both younger than A.
Fossil B is Younger than Fossil A, but older than Fossil C.
Fossil C is the youngest (because its on top).