Which part of the proof does the fourth statement and reason represent?

Given: AB ≅ BC
BC ≅ EF

Prove: EG = AB + FG

A line contains point A, B, C.

A 2-column table has 6 rows. Column 1 is labeled Statements with entries line segment A B is-congruent-to line segment B C, line segment B C is congruent to line segment E F, line segment A B is-congruent-to line segment E F, A B = E F, E G = E F + F G, E G = A B + F G. Column 2 is labeled reasons with entries given, given, transitive property, definition of congruent segments, segment addition, and substitution.

It is part of the given information.
It is part of the argument.
It is the conclusion.
It is an assumption