By looking at all the options, we can see that all of the formulae given have 3 copper atoms. This means that 1 of the molecules ; either CuCO3 or Cu(OH)2 have 2 moles and the other has 1 mole.
1st possibility – 2CuCO₃ + Cu(OH)₂ -> Cu₃C₂H₂O₈
2nd possibility – CuCO₃ + 2Cu(OH)₂ -> Cu₃CH₄O₇
The first possibility is correct as the option is given but the second possibility is not correct as the option is not given.