Answer:
D. assemble : dismantle :: absorb : expel 
Step-by-step explanation:
The synonym analogy refers to writing two words that represent the same meaning. The synonym/antonym analogy represents two words that have opposite meanings. 
For example: in assemble: dismantle example, the words have different meanings.
Assemble refers to fitting, while dismantle refers to pull the pieces apart. In absorb: expel example, the word absorb refers to soaking up and expel refers to ejecting out. 
Therefore, the synonym/antonym analogy is assemble/dismantle and absorb/expel.