Which of the followings is/are symbiotic associations between autotrophic and heterotrophic organisms only? 
(A) Mycorrhiza between fungi and roots of higher plants.
(B) Lichen between phycobiont and mycobiont. 
(C) Coralloid roots of Cycas have cyanobacteria.
(D) Obligate association between Pinus roots and fungi making mycorrhizae.