#### Answer

The correct answer is:
(a) A has the larger terminal velocity.

#### Work Step by Step

We can write the expression for the magnitude of the drag force for a sphere falling through a viscous fluid:
$F_d = 6\pi \eta ~r~v$
A falling object reaches terminal velocity when the opposing drag forces are equal in magnitude to the gravitational force:
$mg = F_d$
$mg = 6\pi \eta ~r~v$
$v = \frac{mg}{6\pi \eta ~r}$
From this equation, we can see that for spheres with the same radius, the sphere with a larger mass will have a larger terminal velocity. Since A has a larger mass, A has a larger terminal velocity.
The correct answer is:
(a) A has the larger terminal velocity.