Have* this is because has* is past tense and have is more appropriate since there are multiple things you are referring too (Mercury, Venus, Earth and Mars). To be honest, these planets have a molten core.
"Friday is the best day of the week" is an opinion
The answer to the question above is probably, resourcefulness. With hunger, it will help an individual to be more resourceful and creative to provide and fulfill the body's needs, which is food. An individual may make a food out of unusual things just to give its body food and energy.
