Answer:
Option: B is the correct answer.
 B. Rhombus; congruent adjacent sides property.
Explanation:
- We know that a parallelogram is a quadrilateral which has two pair of parallel sides.
 
- Also, a parallelogram will be called a rhombus if all the sides are of same length.
 
- That is we may say that a Rhombus is a parallelogram but a parallelogram need not be a rhombus.
 
We are given that:
ABCD is a parallelogram ( this means AB||CD and BC||DA ) and line CD = line DA. 
Hence, the parallelogram is a rhombus by:
 Congruent adjacent sides property.