Use the Following Information and Graph to Answer the Question

Multiple Choice

Use the following information and graph to answer the question.
The figure depicts changes to the amount of DNA present in a recipient cell that is engaged in conjugation with an Hfr cell. Hfr cell DNA begins entering the recipient cell at time A. Assume that a fragment of the recipient cell's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA.
At which time can the recipient cell first be described as "recombinant"?

A) A
B) B
C) C
D) D