Mapping populations are:

Correct option is A

What are Mapping Populations?
Mapping populations are specially developed plant populations used to identify the location (map) of genes or quantitative trait loci (QTLs) on chromosomes.
These populations are derived from genetically distinct parents and display segregation for traits of interest.
✅ Why RILs (Recombinant Inbred Lines) Are Used:
Recombinant Inbred Lines (RILs) are produced by:
Crossing two homozygous parents (P1 × P2)
Producing an F₁ hybrid
Repeated selfing (usually up to F6 or F8) by Single Seed Descent (SSD) method to obtain homozygous but recombinant lines
Advantages of RILs for Mapping:
High level of recombination
Stable genotypes can be replicated across environments
Excellent for QTL mapping and linkage analysis
�� Option-wise Explanation:
(a) RILs – ✅ Correct, widely used in genetic mapping due to recombination and homozygosity.
(b) F₁ generation – ❌ Genetically uniform, shows heterosis but no segregation— not useful for mapping.
(c) Inbreds – ❌ Used as parents, but not mapping populations themselves.
(d) Pure lines – ❌ Uniform and homozygous; not segregating— not suitable for mapping.