Take another look at the sentence:
The message light on the phone was blinking. Eight appointments and an afternoon meeting filled the calendar. A stack of top-priority work _________ in the middle of the desk. Valerie knew that lunch would be a bottled water and a handful of antacid tablets.
The stack of work rested in the middle of the desk. Thus, you need a form of lie. Since the sentence is past tense, you need the simple past form. Consult the table below or review the rules.
|Infinitive||Definition||Simple Present||Simple Past||Past Participle||Present Participle|
|to lay||to put something down||lay(s)||laid||laid||laying|
|to lie||to rest or recline||lie(s)||lay||lain||lying|