Directions: In the following question, two statements are given with some words in bold. Which of the following pairs of bold words must be interchanged to make both sentences grammatically correct?

a. The strategic(A) technical issues were tactical(B) the construction process until the engineers utilized an auger(C) to gain deeper insights and find solutions.

b. The military's stymieing(D) approach involved unforeseen(E) planning and precise(F) execution, ensuring success on the battlefield.