Final answer:
Marco can deduct $23,946 as mortgage interest on his tax return.
Step-by-step explanation:
To determine how much mortgage interest Marco can deduct as an itemized deduction on Schedule A, we need to consider the following:
- Mortgage interest on a personal home is deductible
- Mortgage interest on a vacation home used only for personal purposes is deductible
- Mortgage interest on someone else's home where they are legally liable for the debt is not deductible
- Mortgage interest on a rental property is deductible
Using this information, we can calculate that Marco can deduct $6,048 (mortgage interest on his personal home) + $5,261 (mortgage interest on his vacation home) + $7,642 (mortgage interest on his rental property) = $18,951.
Therefore, the correct option is choice a. $23,946.