Making a water drop in Illustrator is simple. First, create a new document with a width of 600 pixels and a height of 300 pixels. Then, create a circle using the Ellipse tool (L). Next, use the Direct Selection tool (A) to select the inner part of the circle (the part that is closest to the center of the circle).
Finally, use the Pencil tool (B) to create a small line in the center of the circle. This line will be used to create the water drop.