Final answer:
The two distances from the center of the uniform solid sphere where the gravitational acceleration is a/4 are 2R and 0.25R option B.
Step-by-step explanation:
To find the two distances from the center of the sphere where the acceleration due to gravity is a/4, we can use the formula for gravitational acceleration on the surface of a uniform solid sphere:
ag = (G × mass) / (radius^2)
where G is the gravitational constant, mass is the mass of the sphere, and radius is the radius of the sphere.
Setting the gravitational acceleration equal to a/4 and solving for the distances, we get:
r1 = (R √(4/π)) and r2 = (R √(16/π))
where R is the radius of the sphere given in the question.
Therefore, the answer is option B. 2R, 0.25R.