please explain

34. Cassandra is a self-employed physical therapist who operates a qualifying office in her home. Cassandra has $180,000 gross income from her practice and $160,000 of expenses directly related to the business, i.e., non-home office expenses. Cassandra's allocable home office expenses for mortgage interest expenses and property taxes are $14,000 and other home office expenses are $9,000. What is Cassandra's total allowable home office deduction? A) $9,000 B) $14,000 C) $20,000 D) $23.000