Question

One of the following shows complete linkage
A. Male Culex
B. Male Drosophila
C. Female Drosophila
D. Neurospora

Answer 1

When two or more features are inherited and generally surface in two or more generations in their parental or original combinations, the linkage is said to be full. These selected genes do not produce non-parental combinations. The genes that show these connections are found on the same chromosome. Genes that generate a fraction of non-parental combinations display it. Because of the infrequent or inadvertent deconstruction of chromosomal segments while crossing across, these genes are located at a distance on the chromosomes.

Complete explanation:
Option A: In male Drosophila , complete linkage was discovered. If linkage is complete, there should be no recombination and just parental combinations. Morgan made a complete Drosophila link. When a male wild fly with a grey body and normal wings was crossed with a female wild fly with a black body and vestigial wings, the $F1$ hybrids They were all grey, with characteristic wings (with dominant characters).
So, option A is not correct.
Option B: Complete linkage was detected in male Drosophila. There should be no recombination and only parental combinations if linkage is full. Morgan discovered a full Drosophila connection. When a male wild fly with a grey body and normal wings was crossed with a female wild fly with a black body and vestigial wings, the hybrids produced in $F1$ All of them had grey bodies and typical wings (with dominant characters). However, when $F1$ males were backcrossed with recessive female parents, only two types of individuals were produced in the $F2$ generation, rather than the predicted four. The grey body and normal winged, as well as the black body and vestigial winged, were found in similar numbers, demonstrating a perfect relationship.
So, option B is correct.
Option C: These related genes tend to stay together during gametogenesis, but crossing over separates them since they are so far apart. Female Drosophila , maize, tomato, and a variety of other organisms have all been studied for incomplete linkage.
So, option C is not correct.
Option D: “Linkage and recombination are phenomena that define gene inheritance.” Gene linkage and recombination are a result of this.
LGI-LGVII is a haploid filamentous fungus having seven chromosomes (Linkage Groups). Neurospora has two types of mating, A and a, and is incapable of self-fertilization.
So, option D is not correct.

Therefore, Option B is the correct answer.

Note:
As a rule, linkage is incomplete, and most linkage groups' gene pairs assort at least partially independently of one another. Physical crossing over during meiosis between gene pairs on homologous chromosomes can alter linkage, which is a physical interaction between genes.
Linkage disequilibrium will have occurred if random sampling creates an excess of a haplotype in a generation by chance. $A1B1$ haplotypes will have a higher frequency than random mating if individuals with gene $A1$ choose to mate with $B1$ types rather than $B2$ types.