The correct answer is: A. More expensive.
Hard disks are more expensive than diskettes because they have more storage capacity and are more durable. Hard disks can store up to several terabytes of data, while diskettes can only store up to 1.44 megabytes of data. Hard disks are also made of more durable materials, such as metal and plastic, while diskettes are made of more fragile materials, such as paper and plastic.
Option B is incorrect because hard disks are not more portable than diskettes. Hard disks are typically larger and heavier than diskettes, and they require a power source to operate. Diskettes, on the other hand, are small and lightweight, and they can be used without a power source.
Option C is incorrect because hard disks are not less rigid than diskettes. Hard disks are made of more durable materials, such as metal and plastic, while diskettes are made of more fragile materials, such as paper and plastic.
Option D is incorrect because hard disks are not slowly accessed than diskettes. Hard disks can access data much faster than diskettes. This is because hard disks have a faster rotational speed than diskettes.
Option E is incorrect because hard disks are more expensive than diskettes.