Step 1: Understanding the Concept:
The question requires the identification of the correct botanical (scientific) name for the common spice Fenugreek, also known as 'methi'.
Step 2: Detailed Explanation:
Let's analyze the given options, which are all botanical names of well-known plants:
(A) {Papaver somniferum:} This is the scientific name for the Opium Poppy, a source of opium and poppy seeds.
(B) {Trigonella foenum-graecum:} This is the correct and universally accepted botanical name for Fenugreek. It belongs to the family Fabaceae (the legume family).
(C) {Nigella sativa:} This is the scientific name for Black Cumin or Kalonji, another common spice.
(D) {Elettaria cardamomum:} This is the scientific name for Cardamom, also a very popular spice.
Step 3: Final Answer:
Based on botanical nomenclature, Fenugreek (methi) is identified as {Trigonella foenum-graecum}.