The correct answer is option 'C': The cells in DRAM are not static.

Explanation:

DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory) are two different types of memory technologies used in computer systems. While they both serve the purpose of storing data, they have distinct characteristics and advantages/disadvantages.

1. DRAM stores data in individual memory cells, which are composed of a capacitor and a transistor. The data is stored in the form of electrical charge in the capacitors. However, the charge in the capacitors leaks over time, which means that the data stored in DRAM cells needs to be continuously refreshed. This process is called "dynamic" because the cells require periodic refreshing to maintain their data integrity.

2. On the other hand, SRAM stores data in bistable flip-flops, which are composed of multiple transistors. Unlike DRAM, SRAM does not require refreshing, as the data remains stored as long as power is supplied to the memory cells. This makes SRAM "static" in nature, meaning it does not need periodic refreshing.

Now, let's discuss why the correct answer is option 'C': The cells in DRAM are not static.

- DRAM cells are not static: As mentioned earlier, the charge stored in the capacitors of DRAM cells leaks over time. This means that the data stored in DRAM needs to be continuously refreshed to maintain its integrity. The refreshing process introduces additional complexity and overhead in terms of both hardware and software. On the other hand, SRAM cells are static and do not require periodic refreshing, which simplifies the memory architecture.

- Lower data storage capacities (option 'a'): This option is incorrect because DRAM and SRAM can have similar data storage capacities. The capacity of both types of memory is determined by the number of memory cells that can be packed in a given area. However, DRAM is more commonly used for higher-capacity memory modules due to its cost-effectiveness.

- Higher heat dissipation (option 'b'): This option is incorrect because heat dissipation is not a specific disadvantage of DRAM over SRAM. Both types of memory technologies can generate heat when they are in use, but the heat dissipation mechanisms depend on the overall system design and cooling solutions rather than the memory technology itself.

In conclusion, the correct disadvantage of DRAM over SRAM is that the cells in DRAM are not static and require periodic refreshing to maintain data integrity.