Which of the following statements is not true of two genes that show 50% recombination frequency?

The correct option is B The genes are tightly linked
When genes are located very near on the chromosome, they are said to be tightly linked. Tightly linked genes usually have a recombination frequency very close to 0% and hence the statement in option B is not true.

Two genes showing a recombination frequency of 50% are either located on different chromosomes or located far apart on the same chromosome and assort independently.

If the genes are present on the same chromosome, they can undergo more than one crossover in every meiosis

So, the correct answer is option B.