The correct options are
A It is a branch of agriculture that deals with the study of fruits, vegetables, and other ornamental plants.
C Landscape horticulture refers to the production and use of plants to beautify the outdoor environment.
Horticulture is a branch of plant agriculture that deals with the study of fruits, vegetables, herbs, flowers, and other ornamental plants. The three sub-branches of horticulture are pomology (cultivating fruits), olericulture (cultivating vegetables), and ornamental horticulture. Ornamental horticulture is divided into floriculture and landscape horticulture. Floriculture relates to flowers, potted, and bedded plants. Landscape horticulture refers to the production of use of plants to beautify the outdoor environment. Apiculture (beekeeping), pissiculture (fish farming), and aquaculture (cultivating marine creatures) are not a part of horticulture.