The correct response is:
The amount of the gravitational force doubles.
According to Newton's law of universal gravitation, the gravitational force \( F \) between two objects is directly proportional to the product of their masses \( m_1 \) and \( m_2 \) and inversely proportional to the square of the distance \( r \) between their centers:
\[ F = G \frac{m_1 m_2}{r^2} \]
If the mass of one object doubles, while the other mass and the distance remain the same, the gravitational force also doubles.