Density refers to a physical property that is measured using a ratio of divided by so that two objects of the same size can still have very different density?

i know i may be late to answer this but the answer is "mass, volume"

hope this helped

a,b,d are the three sentences that use a reflexive pronoun

martians or other types of aliens represent a unique fear as opposed to zombies. vampires and other types of monsters.   in most sci-fi stories, aliens come from other worlds and have different or more advanced technology.   abductions and experimentation on human bodies that involve these technologies, or the use of these technologies against human beings and the use of unknown "powers", are a type of fear that's different from that of other types of monsters.