A transgenic plant is a plant that has been genetically engineered to contain and express one or more genes from another organism (a transgene).
Let's analyze the options:
(a) Bt Cotton: A well-known transgenic plant. It is genetically modified to express a gene from the bacterium Bacillus thuringiensis (Bt) that encodes an insecticidal protein (Bt toxin), providing resistance to certain insect pests like bollworms.
(b) Golden Rice: A transgenic rice variety genetically engineered to produce beta-carotene (a precursor of Vitamin A) in its edible endosperm. This was done to combat Vitamin A deficiency in populations that rely heavily on rice.
(c) Samba Mahsuri (BPT 5204): This is a popular, high-yielding rice variety developed in India through conventional plant breeding methods (hybridization and selection). It is known for its fine grain quality and good cooking characteristics but is susceptible to some diseases like bacterial blight. Improved versions (e.g., Improved Samba Mahsuri) have been developed using marker-assisted selection and may involve genes from wild relatives, but the original Samba Mahsuri is a product of conventional breeding, not a transgenic plant created by direct insertion of a foreign gene through genetic engineering techniques discussed for GMOs.
(d) FLAVR SAVR Tomato: One of the first commercially grown genetically engineered foods. It was modified to have a longer shelf life by suppressing the gene responsible for producing an enzyme (polygalacturonase) that causes fruit softening. It is a transgenic plant.
Therefore, Samba Mahsuri (the original variety) is not a transgenic plant in the sense of being a GMO created by direct gene insertion. It's a product of conventional breeding.
\[ \boxed{\text{Samba Mahsuri}} \]