Remote spillage (D) is the correct answer because it specifically indicates that a virtual warehouse lacks sufficient memory and local disk space to handle the query's intermediate results. When a query requires more memory than available, data spills to local disk; if local disk is insufficient, it spills to remote storage, signaling that the warehouse is undersized. The community discussion strongly supports this with 100% consensus on D, and detailed comments from users like girgir explain that remote spillage occurs when memory and local disk are inadequate, directly linking it to improper warehouse sizing. Options A (Bytes sent over the network), B (Synchronization), and C (Initialization) are unrelated to warehouse sizing; they pertain to network traffic, coordination processes, and startup activities, respectively, and do not reflect resource inadequacy.