Which of the following statements is true of linkage?
A.
The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.
B.
The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%.
C.
All of the traits that Mendel studied-seed color, pod shape, flower color, and others-are due to genes linked on the same chromosome.
D.
Linked genes are found on different chromosomes.
E.
Crossing over occurs during prophase II of meiosis.

The term crossing over refers to the process which occurs during meiosis in which genetic material is exchanged between two non-sister chromatids from two homologous chromosomes. The process of crossing over is responsible for bringing new genetic combinations and diversities in the offspring which is the main reason why offspring look different from parent and even siblings.

As we know that genes are located on specific positions in chromosomes and if the two genes are very close with each other, they will be inherited together because they are known as linked genes. Therefore, if two genes are very close to each other and also are present on same chromosome, no crossing over will occur between them and the both will be inherited together to the offspring. This type of transfer of two linked genes occurs as a unit.

Please see attached image for better understanding.

Hope it help!