How many types of storage loops exist in magnetic bubble memory?

The correct answer is D. There are two types of storage loops in magnetic bubble memory: single-layer and double-layer.

In single-layer magnetic bubble memory, the bubbles are stored on a single layer of magnetic material. This type of memory is less expensive than double-layer memory, but it has a lower storage capacity.

In double-layer magnetic bubble memory, the bubbles are stored on two layers of magnetic material. This type of memory has a higher storage capacity than single-layer memory, but it is more expensive.

The following are the brief explanations of each option:

• Option A: There are 8 types of storage loops in magnetic bubble memory. This is incorrect. There are only two types of storage loops in magnetic bubble memory: single-layer and double-layer.
• Option B: There are 4 types of storage loops in magnetic bubble memory. This is incorrect. There are only two types of storage loops in magnetic bubble memory: single-layer and double-layer.
• Option C: There are 16 types of storage loops in magnetic bubble memory. This is incorrect. There are only two types of storage loops in magnetic bubble memory: single-layer and double-layer.
• Option E: None of the above. This is the correct answer. There are only two types of storage loops in magnetic bubble memory: single-layer and double-layer.