Final answer:
If Earth had twice its current mass, the gravitational force between Earth and the Sun would double, because gravitational force is directly proportional to mass.
Step-by-step explanation:
If Earth had twice the mass it has now, then the magnitude of the gravitational force between it and the Sun would be doubled. According to Newton's law of universal gravitation, the gravitational force between two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Therefore, if the mass of the Earth were doubled, assuming the distance between Earth and the Sun remains the same, the gravitational force would also double. This is option A) Doubled.