a) event.newValue
b) event.url
c) event.key
d) event.clear

Answer: d
Explanation: There are many storgeEvent interfaces like event.key, event.newValue, event.url, event.oldValue, event.storageArea. Event.key returns the key if the storage item is changed, event.oldValue and event.newValue returns old value and the new value of the key whose value has been changed. Event.url returns the URL of a document which has been changed.