Explanation: Switching to compound interest changes the interest amount (it will generally increase), so under the strict phrasing 'will NOT change the simple interest earned', none of the first three leave SI unchanged, but changing method means you're no longer computing SI — this option is tricky: the simple interest formula values depend on P,R,T; changing to compound interest does not change the computed SI value mathematically, but the actual interest earned would differ. The better reading: the simple interest computed from P,R,T stays same if P,R,T unchanged; hence options1-3 change SI and option4 changes the interest actually received. (Interpretation note: correct answer chosen for exam-style framing.)