13. We observe objects that move and notice changes that happen quickly. Which of the following would be most difficult to observe directly with our eyes? O a fireworks display O boiling water in a pot O burning wood O a temperature change​

its would be the temperature changeing

Explanation:

because you can turn on the fan and other things

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.