The gravitational force between two objects is given by Newton's law of universal gravitation, which states that the force \( F \) is 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 decreases by one-half (let's say \( m_1 \) becomes \( \frac{1}{2} m_1 \)), and the second object's mass (\( m_2 \)) remains the same, the new gravitational force \( F' \) would be:
\[ F' = G \frac{\left(\frac{1}{2} m_1\right) m_2}{r^2} = \frac{1}{2} \left(G \frac{m_1 m_2}{r^2}\right) = \frac{1}{2} F \]
This means the gravitational force decreases by one-half.
Therefore, the correct response is:
The gravitational force decreases by one-half.