Light harvesting complexes are crucial components of photosynthetic organisms, such as plants, algae, and some bacteria. These complexes play a vital role in capturing light energy and transferring it to the reaction center where it can be converted into chemical energy. Light harvesting complexes are composed of hundreds of pigments, making option 'A' the correct answer.

Explanation:
1. Light harvesting complexes: Light harvesting complexes are protein complexes located in the thylakoid membrane of chloroplasts in plants or the plasma membrane of photosynthetic bacteria. They consist of a network of pigments, proteins, and other molecules that work together to absorb light energy.
2. Function: The primary function of light harvesting complexes is to capture photons of light and transfer the energy to the reaction center of the photosystem. The reaction center is where the actual conversion of light energy into chemical energy takes place.
3. Pigments: Pigments are molecules that can absorb certain wavelengths of light. In light harvesting complexes, there are hundreds of pigments that absorb light over a wide range of wavelengths. These pigments include chlorophylls, carotenoids, and phycobilins, which are responsible for the different colors seen in photosynthetic organisms.
4. Absorption and resonance energy transfer: When light strikes a pigment molecule in the light harvesting complex, it excites an electron within the pigment. This energy is then transferred from one pigment molecule to another through a process called resonance energy transfer. This transfer of energy allows the complex to capture a broader range of wavelengths and maximize the efficiency of light absorption.
5. Arrangement and organization: The pigments in light harvesting complexes are organized in a highly ordered manner to optimize light harvesting efficiency. They are arranged in such a way that the energy can be transferred rapidly and efficiently towards the reaction center.
6. Structural proteins: Light harvesting complexes also contain proteins that provide structural support and stability. These proteins help to anchor the pigments in the membrane and maintain the overall integrity of the complex.
7. Role in photosynthesis: Light harvesting complexes are essential for the process of photosynthesis as they enable organisms to capture and utilize light energy. The absorbed energy is then used to drive the production of ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are necessary for the synthesis of organic molecules.
8. Overall importance: The presence of hundreds of pigments in light harvesting complexes allows photosynthetic organisms to efficiently capture light energy from a wide range of wavelengths. This ability is crucial for their survival and growth, as it provides the energy needed for various cellular processes.