Final answer:
The combined mass of the water and sugar is the sum of their individual masses: 20g for water plus 5g for sugar equals 25g total, corresponding to answer B) 25g.
Step-by-step explanation:
When combining substances, such as water and sugar, the mass of the solution is the sum of the mass of each substance. In this case, if the mass of the water is 20g and the sugar is 5g, you would add the two masses together: 20g (water) + 5g (sugar) = 25g (total mass of the solution).
This is because in chemistry, mass is conserved when substances are mixed; they do not lose their mass. Therefore, the combined mass of the water and sugar together would be 25g, which corresponds to answer B) 25g.