Both mechanical and electromagnetic waves a. have compressions and rarefactions b. oscillate in the same direction as the wave motion c. transmit energy d. require a medium for transfer

The correct answer is option C.

That is both mechanical and electromagnetic waves transmit energy.

Mechanical waves required a medium like air to travel but electromagnetic waves doesn't require a medium. Mechanical wave is like sound that travel through air while electromagnetic wave is like light that don't require a medium to travel. But both types of waves transfer energy in a wave-like manner that is both transmit energy.

alchemy hadn't scientific methods of study, appeal to mysticism and fantasy, the knowledge of chemistry and physics were modest at that time.

alchemy was - but as new rules were discovered it either changed into chemistry or it became "unscientific".