Evidence for sea-floor spreading has come from
a.
changes in the
depth of the ocean.
c.
ancient climatic
conditions.
b.
magnetic minerals
on the
ocean floor.
d.
the breakup of
pangaea.

The correct answer is Magnetic minerals on the sea floor

The magnetic minerals behaves like the magnets that aligns themselves during the cooling process. The alignment takes place in the direction of the earth's magnetic field and becomes solidified in this way only. Normal polarity of minerals is having the same polarity like that of earth. In contrast the reversed polarity is alignment opposite to the polarity of the earth.This creates a zebra like pattern.

Thus, this zebra like pattern shows the evidence of sea floor spreading.

chert is a sedimentary rock composed of microcrystalline or cryptocrystalline silica. with this little bit of information, you can come to the conclusion that your answer is c.  

explanation: