Take a look at the sentence again:
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 |