Answer:
(A) Alternate interior angles theorem
(B) Reflexive property
(C) Given
(D) SAS rule of congruency
(E) CPCTC
(F) If both pairs of opposite sides of a parallelogram are congruent, then the quadrilateral is a parallelogram
Explanation:
The two column proof required to prove that EFGH is a parallelogram is presented as follows;
Statement 
 Reason
 Reason
 ║
║
 
 
 Given
 Given
∠FGE ≅ ∠HEG 
 Alternate interior angles theorem
 Alternate interior angles theorem
 ≅
 ≅ 
 
 
 Reflexive property
 Reflexive property
 ≅
 ≅ 
 
 
 Given
 Given
ΔFEG ≅ ΔHEG 
 SAS rule of congruency
 SAS rule of congruency
 ≅
 ≅ 
 
 
 CPCTC
 CPCTC 
EFGH is a parallelogram 
 If both pairs of opposite sides of a parallelogram are congruent, then the quadrilateral is a parallelogram
 If both pairs of opposite sides of a parallelogram are congruent, then the quadrilateral is a parallelogram
Where CPCTC stands for Congruent Parts of Congruent Triangles are Congruent