Answer:
Macro lens
Step-by-step explanation:
A macro lens is used to take photos of small subjects. This lens is capable of photographing images at a ration of 1:1 (or greater), which indicates that the camera is a its closest focusing distance. Photographers often use this type of lens to capture photographs of butterflies, flowers, bees, etc..
If you Google 'macro photography' you can view some examples. Therefore, it is say to say that Susan used a macro lens in her camera to photograph water droplets on a blade of grass.