"Focuses on finding out what consumers want, which wasnt stated at all in the question."
You're not retarded lol, BUT, the whole bit of the question says they developed a product that CONSUMERS WANT, it's the most 'correct' answer since consumers want clothes that do not stain or crumple. It's promotional. They didn't develop a shirt and advertised it, they developed a UNIQUE shirt and advertised it.
With all due respect, you're wrong.
We can all agree that the answer is definitely not A (industrial), since that's a type of market, not a type of marketing approach.
Now the production approach was for stuff like the T-Model Ford and stuff, where it was produced in bulk and bought simply because it was being made. The fact that the question stated that the business "runs an advertising campaign to inform people" about the product clearly rules out production approach as well.
As for the marketing approach, you need to consider the entire question:
"A business develops a shirt made from fabric which never stains or looks crushed. It then runs an advertising campaign to inform people about this product."
Nowhere in there does it mention anything about the wants/needs of any customers, which is key to the marketing approach. Take the dishwasher, for example. If the guy who invented the dishwasher had used a marketing approach, he would have done market research and asked people what they wanted, and they would have said more effective dishwashing liquid and better sponges. Instead, he developed an innovative product, and advertised it to "inform people about this product" and thus persuade them to buy it - ie the selling approach.