The correct statement is (2) ANOVA allows a plant breeder to test whether measurements from three or more treatments show statistically significant differences.

Option-wise explanation

(1) Segregation 1:1 implies two unlinked copies – Incorrect

Statement: “If a transgenic plant heterozygous for an insert segregates 1:1 (transgenic: non‑transgenic) on backcrossing then it contains two unlinked copies of the insert.”

• A 1:1 ratio in a backcross (Tt × tt) is the classic expectation for a single locus that is heterozygous in the donor parent.

• Two unlinked dominant inserts (T₁t₁ T₂t₂ × t₁t₁ t₂t₂) would give 3:1 resistant:sensitive, not 1:1.

• Therefore, a 1:1 ratio indicates one segregating locus, not “two unlinked copies.”

(2) ANOVA in plant breeding – Correct

Statement: “ANOVA allows a plant breeder to test whether measurements from three or more treatments show statistically significant differences.”

• Analysis of variance (ANOVA) is explicitly used to compare means across 3 or more treatments (genotypes, fertilizers, environments) and test if any differ significantly.​

• For only two treatments, a t‑test would suffice; ANOVA generalizes this to many treatments.

• So this statement is accurate.

(3) Comparative genomics: collinearity but not synteny – Incorrect

Statement: “Comparative genomics allows scientists to identify regions of collinearity but not synteny between different species.”

• In comparative genomics, synteny refers to conserved blocks of genes on corresponding chromosomes, while collinearity is the stricter case where both gene content and order are preserved; collinearity is essentially a subset of synteny.​

• Modern tools routinely identify both syntenic and collinear regions between genomes.

• So saying “but not synteny” is false.

(4) RIL population heterozygous at most loci – Incorrect

Statement: “For genetic mapping of a quantitative trait in plants, an RIL mapping population comprising individuals heterozygous at most loci is preferred.”

• Recombinant inbred lines (RILs) are advanced by repeated selfing (F₆, F₇, …) to become highly homozygous at almost all loci; this is precisely why they are excellent for QTL mapping—each line is genetically fixed and can be phenotyped in replicates and environments.​

• A population that is “heterozygous at most loci” describes early F₂ or F₂:₃ families, not RILs.

• Thus this statement is incorrect.

Why option (2) is correct

• Only statement (2) accurately describes its concept (ANOVA); the others misstate classical genetics, comparative genomics terminology, and the nature of RILs.

• Therefore, the correct answer is option (2).