Final answer:
Performance anxiety with the new partner.
Step-by-step explanation:
Erectile dysfunction (ED) is a condition in which a person has difficulty either initiating or maintaining an erection. Possible physiological causes of ED include aging, illness, drug use, tobacco smoking, and obesity, among others. Possible psychological causes of ED include stress, performance anxiety, and mental disorders.
In Brad's case, the more likely cause for his difficulty in maintaining an erection with his new partner is performance anxiety with the new partner (option B). Performance anxiety can occur when an individual feels pressure to perform sexually, which can interfere with the ability to maintain an erection. It is a common psychological cause of erectile dysfunction.