Jane filed her 2018 Form 1040 on April 4, 2019. What is the date on which the applicable statute of limitations expires in each of the following independent situations?
a. Jane incurred a bad debt loss that she failed to claim.
b. Jane inadvertently omitted one-third of the correct gross income.

c. Same as part (b), except that the omission was deliberate.
d. Jane innocently overstated her deductions by a large amount.
e. No return was filed by Jane.