[Clipart] [Open Clip Art Library] Reselling one of your Clip-Art

[noreply at openclipart.org]

Hello 'Open Clip Art Library',
First, thanks for your website ; we use it every day.
I want to know if I can resell a clip-art (in PD licence) I downloaded on your website. Indeed, I work for a web agency and one of my customers liked a clip art we used in one of our presentation. Can we sell it to him or do we need to give him for free ? (It's one of our worst customers so we don't apply sympathy with him but we don't want him to sue us.)
Cordially,
Tristan