Explanation:

Marine fungi, comprising 5% of ocean biomass, play a crucial role in ecosystems, thriving in environments ranging from rocky seashores to deep waters. 

• Marine fungi are crucial for nutrient cycling, and ecosystem stability. 

• Lichens, which represent a symbiotic relationship (fungi and algae living together), also contribute to marine ecosystems.

• Marine fungi are microscopic organisms that live in ocean environments, playing key roles in decomposition, symbiosis, and producing bioactive compounds.

• Types: Obligate Marine Fungi (exclusively marine), Facultative Marine Fungi ( evolved from terrestrial environments, and can survive in marine habitats). 

• Survival Strategies: Marine fungi adapt to feast-famine conditions by changing cell forms for better resource handling.  

• For example, Paradendryphiella salina,found on seaweeds, produces enzymes from bacteria to digest its host. 

• Fungi: These eukaryotic organisms are heterotrophs (consume other plants or animals), functioning as saprophytes (feeding on dead and decaying organisms) or parasites. 

• Fungi reproduce sexually or asexually via spores.  R.H. Whittaker classified Fungi as a distinct multicellular eukaryotic kingdom. 

• Fungi while beneficial in medicine (e.g., antibiotics), food, and industry, can also cause diseases, and produce toxic mycotoxins. 

Hence option 1st is correct because both Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement I.