Which of the following is correctly matched?
(a) Arenchyma - Opuntia
(b) Age pyramid - Biome
(c) Partheniumhysterophorus - Threat to biodiversity
(d) Stratification - Population
(c) Parthenium hysterophorus (carrot grass) is an alien species introduced inadvertantly for some economic use, turned invasive causing decline or extinction of the indigenous species.
The other options are wrong because
(a) Aerenchyma is found in aquatic plants (Vallisneria,Hydrilla), but Opuntia is xerophytic plant.
(b) Biome is total sum of all ecosystem present in the planet earth whereas age pyramid is the graphical representation of age of organisms of one population at a specific time.
(d) Stratification is related with different layers of vegetation in an ecosystem (like forest/grassland) and population is a term referred to a group of same kind of organisms which can freely interbreed.