Which figures amongst B, C, D and E will have to be joined along with figure A to together form a complete square?

The given figure is embedded in which of the following options.

Choose the alternative figure which is embedded in the problem figure :

Fill the missing number (?) in the given figure.

Find out which of the answer figures completes the figure matrix?

Choose three options which when fitted into each other would form a complete square.

The missing figure is to be identified from a set of alternatives, so as to complete the matrix.