The sentence formation in the above case is corrected by replacing “learn” by “tell”. This is because “learn” is a task that needed to be performed by noun (subject).
Therefore, the “learn” is the incorrect word that should not be used in the above case.
Thus, the options (d), (b) and (a) are incorrect.
The sentence formation in the above case is corrected by replacing “learn” by “tell”. This is because “learn” is a task that needed to be performed by noun (subject), which is unsuitable to use in that case.
Therefore, the correct option is – c. learn.