Which image shows natural selection leading to the increase in a specific trait in a population

Astudent conducts an experiment to determine how the amount of water given to a plant affects it growth what is the dependent variable for this experiment

Amale bird-of-paradise uses a dance to attract mates in which it flaps its tail feathers on the ground and jumps around a potential female mate. a different male bird-of-paradise does a similar dance but it jumps around the female in the opposite direction. the female bird is only attracted to one style of dance, in one direction. this is an example of speciation.

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