John accompanied his wife Ling on a business trip to San Diego because Ling is paralyzed from the waist down and confined to a wheelchair. John was not associated with Ling's business directly, but he performed services such as helping Ling overcome architectural barriers, carrying her luggage, facilitating security inspections of Ling at airports, and helped her board the airplanes. We must address the tax treatment of the incremental expenses for John accompanying Ling on the trip?
a. Which BNA portfolio will answer the question?
b. Can John and Ling deduct the cost of the incremental expenses for John accompanying Ling on the trip? List your primary sources of authority that you used to answer this question.