In each row, the second figure is obtained from the first figure by reversing the direction of the RHS arrow and the third figure is obtained from the second figure by reversing the direction of both the arrows.

There are 3 types of faces, 3 types of hands and 3 types of legs. Each type is used once in each row! So, the features not used in the first two figures of the third row would together form the missing figure.

Figure D can be formed from the pieces given in figure X.

Figure A can be formed from the pieces given in figure X.

The pattern here followed is,

In alternate steps, a new triangle is added below the existing triangle in the upper left corner, and a new square is added below the existing square in the lower right corner.

Also, in alternate steps, a new triangle is added over the existing triangle in the lower-left corner, and a new square is added over the existing square in the upper right corner.

The image obtained when paper is unfolded is,

The least possible Venn diagram is:

Conclusions:

I. Some gold are metals $\to$ False (As, there is no definite relation between gold and metal. Hence, false)

II. All metals are diamond $\to$ True (As, All metals are silver and All silver are diamond $\to$ All metals are diamond)

III. Some silver are marble $\to$ False (As, there is no definite relation between silver and marble. Hence, false)

IV. All gold are marble $\to$ False (As, Some gold are marbles)