The question provides us a table of information for different reactions conducted between HCl and NaOH and requires us to explain why a similar amount of NaOH should be expected for reactions 1 and 4.
If we take a look at the table, we can gather the following information:
Reaction 1: 20 drops 0.1 M HCl + 43 drops NaOH
Reaction 4: 20 drops 0.1 M HCl + 20 drops H2O + 63 drops NaOH
Comparing the concentration of HCl solutions used for reactions 1 and 4, we can see that they are the same. The only difference was that an amount of water was added to reaction 4, therefore slightly diluting the solution. However, the amount of HCl in solution (in moles) remained the same, despised the volume of reactant used in reaction 4.
For that reason - the volume and concentration of HCl in both reactions was the same, thus the amount of HCl was also the same - we should expect the same amount of NaOH to neutralize the acid.
However, the number of drops of NaOH observed was different for reactions 1 and 4 (bigger for reaction 4). We could associate that with an experimental error, probably the amount of drops of NaOH for reaction 1 was higher than 43 and the observer couldn't count that (considering the data from table 2 for reactions 1 to 4).