Mr. X, a builder, contracts to erect and finish a house by the 1st January, in order that Mr. B may give possession of it at that time to Mr. C, to whom Mr. B has contracted to let it. Mr. A is informed of the contract between Mr. B and Mr. C. Mr. A builds the house so badly that, before the 1st January, it falls down and has to be rebuild by Mr. B, who in consequence, loses the rent which he have received from Mr. C and is obliged to make compensation to Mr. C for the breach of his contract.

The correct answer is D. All of the above.

Mr. A must make compensation to Mr. B for the cost of rebuilding the house. This is because Mr. A breached his contract with Mr. B by not building the house to a satisfactory standard. As a result, Mr. B had to incur additional costs in order to rebuild the house.

Mr. A must also make compensation to Mr. B for the rent lost. This is because Mr. B was unable to let the house to Mr. C as a result of Mr. A’s breach of contract. As a result, Mr. B lost out on the rent that he would have received from Mr. C.

Finally, Mr. A must also make compensation to Mr. B for the compensation made to Mr. C. This is because Mr. B was obliged to make compensation to Mr. C for the breach of his contract. As a result, Mr. B incurred additional costs in order to compensate Mr. C.

In conclusion, Mr. A must make compensation to Mr. B for the cost of rebuilding the house, the rent lost, and the compensation made to Mr. C. This is because Mr. A breached his contract with Mr. B and caused Mr. B to incur these additional costs.