In this question, we are given four options labeled as A, B, C, and All equal. We need to determine which block is the heaviest one.

Option 1 states that block A is the heaviest. Option 2 states that block B is the heaviest. Option 4 states that all the blocks are equal in weight.

However, the correct answer is option 3. This means that block C is the heaviest.

It is important to note that the question mentions that all the blocks are made of the same material. Therefore, the only differentiating factor in their weight should be their size or shape. Since block C is stated to be the heaviest, it implies that it has a larger size or different shape compared to the other blocks.

In conclusion, block C is the heaviest out of the given options, while blocks A and B are lighter.