Final answer:
Simply replacing an old concrete patio with a new single piece of concrete will not solve the problem of cracking. Proper joints are necessary in the design of a concrete structure to allow for controlled expansion and contraction. Option b is the correct answer.
Step-by-step explanation:
The question deals with the issue of cracking in concrete structures. Concrete, although strong, is not entirely impervious to cracking due to various factors such as thermal expansion and contraction, settling, and overload. To prevent cracking, it's not sufficient to simply replace old concrete with new concrete.
Concrete needs to have proper joints, which act as planned points of weakness where the concrete can expand and contract without causing random, uncontrolled cracking. These joints are placed at specific intervals to control where the cracks will occur, usually in hidden or less noticeable areas.
Therefore, the replacement of the old concrete patio with a new single piece of concrete will not necessarily solve the cracking problem. The mentioned correct option in the final answer is "no, because concrete needs joints to prevent cracking".