Which of the following will complete the adjoining figure?

The correct answer is Option (1) → 

The four quarters are the same design turned about the centre: in each, a pin with a small circle starts from the centre of the whole figure, a quarter of the central circle curves through it, and inward-curving arcs run from the outer corner. In the missing bottom-left quarter the centre is its top-right corner, so the pin must start there, as in Option (1), and its arcs then join those of the neighbouring quarters.