Option (A) is the correct answer. The provided text defines biodegradable substances as those that are 'broken down by biological processes' by microorganisms like bacteria and fungi (decomposers). The text implies that standard plastics are non-biodegradable by mentioning that 'new types of plastics which are said to be biodegradable are available' and linking packaging waste to non-biodegradable materials. Therefore, option (B) is incorrect because it contains plastic. Grass and flowers are plant products, and leather is derived from animal skin; all are organic 'dead remains' that decomposers can break down. Thus, the group 'Grass, flowers and leather' contains only biodegradable items.