How to pull column headings into another column for sorting sizes

I work for a charity and downloaded the info from the registration site. It came to me with all the t-shirt sizes running in separate columns across the sheet by sizes (small, medium, large, xlarge). Entrants are in the far left column. They size they indicated during online reg shows up as a 1 in a column. All the other columns display 0 across their row.

Is there a way to put a formula into a new column that would look know which column the "1" is in and also put the column heading name (which is the size of shirt selected" ---- into that new column next to their name?