A store sells three types of flash drives: brand A, brand B, and brand C. Of the flash drives it sells, 60% are brand A, 25% are brand B, and 15% are brand C. The store has found that 20% of the brand A flash drives, 15% of the brand B flash drives, and 5% of the brand C flash drives are returned as defective. If a flash drive is returned as defective, what is the probability that it is a brand A flash drive? A brand B flash drive? A brand C flash drive?