Answer:
I believe that it is the 2nd option.
Explanation:
My reasonings are because C4H10O has 7 isomers. In which 4 are alcohol and the other 3 are ether.
The first option is ethers, specifically ethoxyethane.
The third option is ethers, specifically 1-methoxypropane.
The fourth option is an alcohol, specifically 1- butanol.
Therefore, leads us to the 2nd option that it is NOT an isomer of C4H10O
