Take another look at the sentence:
At the beginning of the semester, Joyce anticipated learning about Egyptian archeology. Her interest __________, however, as the monotonous lectures of Dr. Nelson provided facts dustier than mummy wrappings.
The sentence requires the simple past of shrink, an irregular verb. Shrank is the simple past form.
|Verb||Simple Present||Simple Past||Past Participle|
Shrinked, the form you chose, is a spelling error. Before you continue, review the rules for irregular verbs.