The correct mirror image of the given figure when the mirror is held at the down side is:

Hence,  "option (4)"  is the correct answer.

  Alternate Method

In Mirror image  left side and right side changed vice-versa where top and bottom remain same.

Reflection of an object into the water  is its  water image . It appears by inverting an  object vertically i.e. upside down.

The water image of the figure looks like the mirror image of the figure in case the mirror is  horizontally at the bottom o f the figure.

Water image  is just a  reflection where top and bottom part of the images changed  where  left and right side of the image remain same.