Gravitational lensing (a) occurs when light passes near a massive object and is deflected by the object's gravitational field.(b) occurs when the mass of a galaxy is greater than expected from the luminosity of the galaxy.(c) can be used to determine the recessional velocity of a galaxy.(d) can be used to determine the luminosity of a galaxy.

(A) occurs when light passes near a massive object and is deflected by the object's gravitational field.

Explanation:

Gravitational lensing occurs when a mass distribution of matter is able to bend the light coming from a source as light travels towards the observer. This effect was predicted by Einstein's general theory of relativity. A galaxy cluster is a mass distribution that acts as a gravitational lens. This effect allows us to see what is behind the sun. As the mass of the sun is very large light curves around the sun.

two charges are fixed in place on the x-axis as shown. the charge at x = 0 is negative and has magnitude q = 2 μcoulombs (1 μcoulomb = 10-6 coulombs). the charge at x = d, (d = +12 cm), is positive and has magnitude q = 4 μcoulombs. find a point x = xo along the x-axis at which the electric field is zero.