In the simplex method, how is a pivot column selected? A pivot row? A pivot element? Give examples of each.

Question; In the simplex method, how is a pivot column selected? A pivot row? A pivot element? Give examples of each.
Answer/Explanation:
I am explaining the above all queries with a Linear Programming problem (LPP) that How is a pivot Column, Row and Element selected?
Which we will solve by simplex method.
Let us consider A Linear Programming problem
Maximum Z =
123
325
xxx
++
 Subject to the constraints
1231312
2430,32460,4420
xxxxxxx
++£+£+£
And
123
,,0
xxx
³
Maximum Z =
123456
325000
xxxxxx
+++++
 Subject to the constraints
123456
123456
123456
200430,
30200460,
4000420
xxxxxx
xxxxxx
xxxxxx
+++++£
+++++£
+++++£
And
123456
,,,,,0
xxxxxx
³
To solve the above LPP convert the inequality constraints to equations by introducing the non negative Slack variables
456
,,
xxx
. The Coefficients of Slack variables in the objective function are taken zero.
Therefore the given LPP now becomes
Maximum Z =
123456
325000
xxxxxx
+++++
 Subject to the constraints
123456
123456
123456
200430,
30200460,
4000420
xxxxxx
xxxxxx
xxxxxx
+++++=
+++++=
+++++=
And
123456
,,,,,0
xxxxxx
³
Present the constraints in matrix...