In a broadcast join, the smaller DataFrame (B, 1 GB) is sent to all executors to avoid shuffling the larger DataFrame (A, 128 GB). Broadcasting B eliminates the need to shuffle B itself (since it is distributed via broadcast) and also avoids shuffling A (as each partition of A can join locally with B). Both options B and D correctly describe parts of this reasoning: B focuses on avoiding B's shuffle, while D emphasizes avoiding A's shuffle, which is critical due to A's larger size. Thus, both B and D are correct.