D. Each line contains two red dice and one blue die. Each line contains a two, a three and a five. The missing image is of a red die, number three.

An octagon. Each shape has the same number of sides as the sum of the sides of the two shapes below it. If the number is over 10, then the last digit is used instead. For example, 9 + 8 = 17 so the brick above is 7-sided. The top shape is an 8-sided octagon because there are two 4-sided shapes below it.

RED or TAN. The number of letters in each tile is one less than those in the following row. Hence, there must be only three letters in the empty tile.

Is there a riddle stuck in your brain, and you cannot solve it? Be happy! It is a positive proof that you have a brain.

A palm.

A stamp.

A coin.

A towel.

A needle.

A mushroom.

Roman Numerals: FIVE take away F and E which leaves IV which is 4 in Roman Numerals.

Fish.

* The above content is picked from various resources.