Answer:
A. Appreciates
Step-by-step explanation:
Because (b) 'can be appreciated the aroma' is using incorrect past terms in a current action. (c) 'appreciate the aroma' is grammatically incorrect because all the other verbs 'inhales', 'smiles', and 'walks' are all present terms. And (d) 'will have appreciated the aroma' is using past terms in an answer that uses active verbs.