The microbes, mostly fungi and sometimes bacteria, that grow entirely within the plant body, inter or intracellular and spend all or nearly all their life cycle in the host are called:

Correct option is A

Endophytes are microorganisms— mainly fungi and sometimes bacteria—that live inside plant tissues without causing any immediate, overt negative effects to the host plant. They exist either in intercellular spaces (between cells) or intracellularly (within cells).
�� Characteristics of Endophytes:
· They spend all or most of their life cycle within the plant.
· Commonly found in roots, stems, leaves, and seeds.
· May be mutualistic (beneficial), providing:
· Enhanced drought resistance
· Improved nutrient uptake
· Disease resistance by producing secondary metabolites
· Protection against insect pests or herbivores
· Some endophytes produce bioactive compounds, including antibiotics, alkaloids, and growth hormones.
They are of great interest in agriculture and biotechnology for their potential in biological control, stress tolerance, and sustainable crop production.
❌ Explanation of Incorrect Options:
(b) Antibiotics:
· These are chemical substances produced by microbes to inhibit or kill other microorganisms.
· They are not organisms themselves, and they do not live in plants.
(c) Biotypes:
· Refers to a group of organisms within a species that share a specific genetic trait, often used in pest and pathogen classification.
· Biotypes are not defined by living inside plant tissues.
(d) Genetics:
· This is the scientific study of genes, heredity, and variation.
· It is not a term used to describe a group of plant-associated microbes.