Option 1 -> "councillled" is a misspelling and not a valid word in this context.
Option 2 -> "consoled" means to comfort someone, which doesn't fit the context of directing someone to follow a plan.
Option 3 -> "counselled" means advised or gave guidance, which fits perfectly when the architect is recommending plan B.
Option 4 -> "cancelled" means to call off something, which doesn't make logical sense in this sentence structure.
Hence, Option 3: counselled -> The architect advised/guided the engineer to follow plan B. "Counselled" (British spelling) means to give professional advice or guidance, which is appropriate when discussing professional direction between colleagues. -> correct