Explanation:
An optimizer compiler is a type of compiler that is designed to optimize the code during the compilation process. It aims to improve the performance of the compiled code by making it more efficient and reducing the amount of resources it requires.

Occupying less space:
One of the main goals of an optimizer compiler is to minimize the amount of space that the compiled code occupies. This is achieved by performing various optimizations on the code, such as eliminating unnecessary instructions, reordering code to minimize memory usage, and reducing the size of data structures. By optimizing the code, the compiler can generate a more compact and efficient executable file.

Optimizing the code:
In addition to reducing the space occupied by the compiled code, an optimizer compiler also aims to optimize the code itself. This includes improving the performance of the code by reducing the number of instructions executed, eliminating redundant computations, and optimizing memory access patterns. The optimizer compiler analyzes the code and applies various optimization techniques, such as loop unrolling, constant folding, and instruction scheduling, to generate a more efficient version of the code.

Both of the mentioned:
Therefore, the correct answer is option 'b' - an optimizer compiler is optimized to occupy less space and to optimize the code. These two goals go hand in hand, as reducing the space occupied by the code often involves optimizing the code itself.

None of the mentioned:
Option 'd' - None of the mentioned is incorrect because an optimizer compiler is specifically designed to optimize the code and reduce its space requirements.