The first three choices: a, b and c can be considered reconstruction except the last one which is letter d. I'm not really certain what reconstruction is, but judging from the patterns of the first three choices, reconstruction could mean that an inference is made after a part of an event has proved that event to be true.
Given :
An electron moving in the positive x direction experiences a magnetic force in the positive z direction.
To Find :
The direction of the magnetic field.
Solution :
We know, force is given by :
Here, q = -e.
Now, for above condition to satisfy :
So, 
Therefore, direction of magnetic field is negative y direction.
Hence, this is the required solution.
We Know,
K.E. = 1/2 mv²
480 = 1/2 (m)(8)²
m = 960/64
m = 15 Kg
So, the mass of the object is 15 Kg
Answer is Global Warming causes destruction of our ecosystem due to increased temperatures, drought, fire, weed and pest infestations, more intense storms, water shortages, melting ice caps and glaciers, air pollution.
