Concept:Use the tangent addition formula and then expand the required product.Explanation:Given x+y=4π, take tangent on both sides.tan(x+y)=tan4π=1Using the formula tan(x+y)=1−tanxtanytanx+tany, we get:1−tanxtanytanx+tany=1Cross-multiplying:tanx+tany=1−tanxtanyRearranging:tanx+tany+tanxtany=1Now expand the required expression:(1+tanx)(1+tany)=1+tanx+tany+tanxtanySubstitute the known value:(1+tanx)(1+tany)=1+1=2Answer:The correct answer is 2, which is option B.