Shauna was killed one Sunday morning. The police know who they are going to arrest from this bit of information:
April was getting the mail
Alyssa was doing laundry
Reggie was cooking
Mark was planting in the garden
Who killed Shauna and how did the police know who to arrest?
April killed Shauna because there is no mail delivery on Sundays.
What is as big as an elephant but weighs nothing?