<span>The answer is transformer. They utilize
electromagnetic induction to generate current. This is only possible in
alternating current due to the differential increase and decrease of electrical
current that induces changes in magnetic flux in the coil. This varies the
magnetic flux of the primary coil that generates current in the secondary coil.</span>
Answer:
Because the gravitational attraction of the Sun hold them in motion around it
Explanation:
For an object travelling in a straight path at constant velocity, the net force acting on the object must be zero.
The planets in the Solar System, however, do not experience a zero net force: in fact, the Sun exerts a gravitational attraction on them, whose magnitude is given by

where
G is the gravitational constant
M is the mass of the Sun
m is the mass of the planet
r is the average distance between the Sun and the planet
Due to the presence of this force, the Sun makes the planets 'deviating' from their straight path, forcing them to following an elliptical path around the Sun.
I beileve the answer is B