For a gravitational field to be generated between two objects, what must be true? No other forces can be presents
The two objects must be in contact
One object must be pure iron
Both objects must have mass

D. Both objects must have mass

Explanation:

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.

the correct answer would be d. hope this !