(a) A retailer or wholesaler with intent to injure a competitor or to destroy competition may not advertise, offer to sell, or sell at retail sale or wholesale sale any item of merchandise at less than its cost to the retailer or its cost to the wholesaler, respectively.
(b) Proof of an advertisement, offer to sell, or sale of an item of merchandise by a retailer or wholesaler at less than its cost to the retailer or its cost to the wholesaler, respectively, is prima facie evidence of intent to injure a competitor or to destroy competition.