Coal was formed
a. from trees, ferns, and other plants that predate the dinosaurs
b. from remains of fossilized dinosaurs and the plants they fed on
c. from aquatic organisms buried under silt and sediment
d. beginning almost 800 million years ago

A) from trees, ferns, and other plants that predate the dinosaurs

Explanation:

Just in case they decide to switch the answer letters around.

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

hope this .. .