Concept:A logarithm gives the exponent of 10. Here the characteristics are negative, so use bar notation: 2.3675=−2+0.3675.Explanation:x=102.3675=10−2+0.3675=10−1.6325≈0.02331.Similarly, y=102.9738=10−2+0.9738=10−1.0262≈0.09414.Therefore, x+y≈0.02331+0.09414=0.11745.Correct to three significant figures, look at the fourth significant digit: 0.11745 has digits 1,1,7,4, so it rounds to 0.117.Answer:0.117 (Option C).