Why would anybody agree with any one of those statements? "Well, because one of those is true," you might reply, and I can guess which statement that would be. But why do you think it is true? In no area of human knowledge do we accept that the rules that govern the universe are subject to personal opinion. Why do you think the morality of an act is subject to your personal whim?
American society (and I suspect others) drill into our heads constantly that there is no such thing as right and wrong, that moral knowledge is not knowledge, that right and wrong are just opinions. Yet, they expect us to follow laws. Why? If rape is right for me, why can't I do it? You can't say because it is wrong, because there is no right or wrong, remember? Oh, because it hurts someone, you say? But so does abortion. And now we're back where we started.
People who claim that morality is relative really mean that only the things that they want might want license to do are relative, and other things are. They will find it OK to restrict what we eat, because eating poorly would cause health problems down the line, but encourage homosexual activity that will cause health problems down the line.
If someone said that the weight of a pound was different for different people in order to make more money selling you stuff you'd stop them pretty quickly. Why should you accept that someone can do something else that's objectively wrong? The classic objection is that different people have different ideas about what's right and wrong? That's true, but different people also have different ideas about where Colorado is on a US map. Their ideas are mistakes or ignorance, and are not accepted as truth. People who believe in moral relativism are the modern day equivalent of flat earthers.
So, who's idea of right and wrong is the "right" one? For that we have to accept morality as a real branch of knowledge based on postulates and logic, just like mathematics. It is a real branch of knowledge, and the moral order as defined by the Catholic Church is based on the natural law - the order of things in the universe. It is not some arbitrary thing that dropped from the sky. For instance. the moral law tells us that killing an innocent human being is wrong. That is a premise. Science tells us that an embryo (or fetus) is a human being. Abortion kills an embryo (or fetus). Therefore abortion is wrong.
To contradict the statement "abortion is wrong" you have to either argue that abortion doesn't kill (it does), a human embryo is not alive (it is), a human embryo belongs to another species (it doesn't), an embryo is not innocent (which implies evil intent) or that it is OK to kill innocent human beings. If you want to disagree with the premise that it is wrong to kill innocent human beings, then we can talk, but let's at least be honest and admit that the statement was properly reasoned from the premise and that the premise is a reasonable one.
Sorry if this post seems to ramble a bit - I've had a day of people arguing vociferously about morality being baseless, irrelevant and arbitrary, and so I'm taking it out on you, dear reader.