I would say 2 and 3 at this point only because I know really nothing about 1 and 2.
#1 basically goes like this:
When an egg is fertilized, a normal pregancy will begin with the egg implanting itself in the woman's uterus, which has enough space to house a full-sized baby. An ectopic pregnancy is where the egg implants itself elsewhere, usually in the fallopian tubes. The fallopian tubes are only wide enough to allow a single egg through. If the egg grows normally within the fallopian tubes, the woman will be subjected to extreme and excruciating pain and eventually death as the embryo expands and causes the fallopian tube to tear and rupture. The only way to avert this is to remove the embryo.
That's an ectopic pregnancy in a nutshell.