Doing Two Things at Once

When I was working as a layout artist at Sears, we had to take a time management seminar. I remember one of the questions was: What would you do first if (simultaneously) your phone was ringing, your baby was screaming, and someone was knocking at your door? I’m never good at answering questions like that, so I was the only one who chose the baby—and I didn’t even have children at the time.
Because this was the wrong answer, the seminar leader turned me into the example of what not to do. I didn’t understand his reasoning, and I can’t recall what I should have done. This was back in the days before answering machines and cell phones, so obviously something had to be done first…I think it was answer the phone, ask the person calling to hold on, and then answer the door. (Presumably the baby was just being a pest). I do remember him saying that I was obviously a person who had trouble doing two things at once. Right you are buddy, but it works for me.
The only time I can multitask is if I’m talking on the phone to someone I know well. (Sorry Pam, Beverly, Mum etc.) Then I usually play around in Photoshop at the same time, or I might tidy up. If the person is right in the room with me though, I have to drop everything. How can you talk to someone without looking them in the eye?