Select the figure from among the given options that can replace the question mark(?) in the following: series.

In the first figure, from the left, five circles are there and they are not connected with each other.

In the second figure, from the left, two circles are connected with each other.

In the third figure, from the left, three circles are connected with each other.

In the fourth figure, from the left, four circles are connected with each other.

Similarly, in the fifth figure, from the left, five circles will be connected with each other.

Now in each option, five circles are available. But options (b), (c), and (d) can be eliminated. Because of the different patterns in connection of the circles.

Hence option (a) is remaining which will be the most appropriate figure in place of the question mark.