I'm not sure about this, but it says list all your trip and if applicable your family members basically their asking applicant's travel history not the sponsor's..
A . you (applicant) is applicable to your case but not letter B I guess .. Since the form is generic it's not only for spouse sponsorship, it applies to other applications too.. Ex, both couple are applicants so A is applicable for the primary applicant and B for applicable for his/her partner ... In your case, your spouse is your sponsor so it's not applicable to you.. You can just skip it... That's what I did too..