I need help with this

Which best describes how the common cold spreads in the human body? a bacteria burst out of normal cells killing them b viruses replicate inside respiratory cells c bacteria inject dna into normal cells d viruses insert dna into bacteria

Of seawater increases with decrease in the temperature. therefore, the cold water sinks to the deeper layers at the bottom

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating