Explanation

The plant BbMm produces four types of gametes (BM, Bm, bM, bm) in equal proportions (1/4 each). The probability of a specific gamete (bm) fertilizing another specific gamete (BM or bm) depends on the context. However, if we assume random fertilization between two such plants, the chance of any specific combination is 1/4 * 1/4 = 1/16. But the question asks for the possibility of (bm) gametes fertilizing either (BM) or (bm). This phrasing is ambiguous. If it means the probability of a bm gamete being produced, it is 1/4. If it means the probability of a bm gamete fusing with a BM or bm gamete from another parent, it's more complex. Given the options, 1/4 is the standard answer for the frequency of a specific gamete type in independent assortment.