Why Should Scarring of a Fallopian Tube Raise the Risks

Why should scarring of a fallopian tube raise the risks of an ectopic pregnancy?

A) Scarring may slow the progression of the ovum (egg) from the fallopian tubes into the uterus. If it is fertilized by a sperm cell while it is stopped in the fallopian tube, it may implant there, resulting in an ectopic pregnancy.
B) Scarring can completely block the ovum (egg) from being able to exit the fallopian tube to enter the uterus. It may implant in the wall of the fallopian tube (since it can't enter the uterus) and result in an ectopic pregnancy.
C) Scarring may allow the sperm cells to enter the fallopian tubes and bind to the scar tissue. The inflammatory response generated when this occurs is termed an ectopic pregnancy.
D) Scarring of the fallopian tubes results from undiagnosed bacterial infections. These bacteria can also make the lining of the uterus inhospitable to implantation of a fertilized egg. If the fertilized egg can't implant into the wall of the uterus, it may travel back into the fallopian tube and implant there instead, resulting in an ectopic pregnancy.