Correct Answer: (a) Chandragupta Maurya
Solution:Few centuries before the Christian era, the Mauryan emperors, Chandragupta Maurya and Ashoka focussed on the water resource management in Girnar region. The Governor of Chandragupta Maurya's Western Province Pushyagupt built Sudarshan Lake and The Governor of Emperor Ashok, Tushasp took out canals from the lake. The Junagarh inscription of Shaka ruler Rudradaman describes the works of both Chandragupta Maurya and Ashoka. 2 century A.D., the lake was repaired by the Governor of Rudradaman Suvisakh. According to the question, he did this work after the Christian era. Thus he is not included in the answer, so the correct answer for the question is Chandragupta Maurya and Ashoka.