During pachytene, translocation heterozygote exhibits:

Correct option is B

During pachytene, a translocation heterozygote exhibits a cross-shaped configuration. 

Explanation:

• Translocation heterozygote: 

This refers to an individual carrying one normal chromosome and one chromosome with a translocation (a piece of one chromosome attached to another chromosome). 

• Pachytene stage: 

This is the phase of meiosis where chromosomes become fully condensed and homologous chromosomes pair up. 

• Cross-shaped configuration: 

When a translocation occurs, the involved chromosomes can form a cross-like structure during pachytene as they attempt to pair with their homologous counterparts, resulting in the characteristic cross shape. 

Why other options are incorrect:

• A - Loop configuration: 

While loops can occur in certain chromosomal situations, they are not typical for translocation heterozygotes during pachytene. 

• C - Ring configuration: 

Rings can form in some cases with quadrivalents (involving all four chromosomes involved in the translocation), but cross configurations are more common in translocation heterozygotes. 

• D - None of these: 

This is incorrect, as translocation heterozygotes clearly exhibit a specific configuration during pachytene.