In the following question, the sentence with two blanks is to be filled with appropriate words. Select the correct alternative out of the four and indicate it by selecting the appropriate option.
Scientists, ________ NASA’s Lunar Reconnaissance Orbiter (LRO), have observed water molecules moving ________ the dayside of the moon, the U.S. space agency said, an advance that could help us learn about accessibility of water that can be used by humans in future lunar missions.
1
were using, away
2
using, around
3
were using, around
4
using, away
5
have used, revolve