Final answer:
Lynn is hesitant because leaving the potato salad out in the sun can lead to bacterial growth. Greta should keep the potato salad in a cooler with ice packs to maintain its temperature.
Step-by-step explanation:
Lynn is hesitant about Greta dropping off the potato salad at 10am because leaving the potato salad out in the sun for 4 hours can lead to bacterial growth and foodborne illness. Bacteria can multiply rapidly in the warm temperature, especially in perishable food like potato salad. If Greta's potato salad sits out in the sun until the picnic begins at 2pm, it may become unsafe to eat and could potentially make people sick if they consume it.
A suggestion to solve Greta and Lynn's problem is for Greta to keep the potato salad in a cooler with ice packs to maintain its temperature until the picnic starts. This will help prevent bacterial growth and ensure that the potato salad stays safe to consume during the event.