To find the unit rate of muffins per cup of almonds, you divide the total number of muffins by the total number of cups of almonds.
Manny makes 36 muffins and uses 4 cups of almonds:
\[ \text{Unit rate} = \frac{\text{Number of muffins}}{\text{Cups of almonds}} = \frac{36}{4} = 9 \]
Therefore, the unit rate is 9 muffins per cup of almonds.
The correct response is: 9 muffins.