Girls Don't Have to Like Pink

After observing the data below, Stanley concluded, "I don't think very many girls took this survey." Why do you think he would say that? 

Students' Favorite Colors 
17 students chose red.
12 students chose blue.
8 students chose green.
4 students chose pink.
41 students took this survey.

What would you put as the answer to a question on a sixth grade math test such as the above?
I was shocked. My jaw dropped open and I was this close to ripping up the test.
I'm sure 99% of the class put, "Since most girls like pink, and not that many students said pink was their favorite color, Stanley probably thought that not many girls took the survey."
You want to know what I answered?
"Although not all girls like pink, Stanley probably doesn't understand that and thought that not many girls took the survey because pink was not popular among the students." I underlined "all" five times and wrote in the corner of the page, "I don't feel so great about this question," and boxed it twice. And I don't honestly care if points get taken off because part of my answer was "unnecessary." It was one of the smallest, gutsiest things I've ever done.
(By the way, yes, sixth grade math can be lame. I would've liked to do more advanced math but I go to a public elementary school so that's not an option.)
Do stereotypes like these really have any place on an elementary school math test, for God's sake?
Girls are constantly picked on for their interests. They grow up believing that no boy will like them if they like pink or aren't a star basketball player. They push themselves toward these hobbies, but only for one reason: They want to be liked.
But what if they like pink and prefer to engage in activities other than athletics? What do they do when society tells them they can't be who they are? That's when their confidence drops.
So did there really have to be a question on my math test asking me whether all girls like pink? I was literally shouting expletives and arguing with this Stanley kid in my head.
What do you think?

NOTE: I recently read an Israeli study that proved that (in Israel at least) there IS a gender-based grading bias. The study was on a handful of sixth grade boys and girls. The girls did not score as well when the teacher knew their gender, but when the teacher actually did not know whether they were a boy or girl, the girls outscored the boys.