Thoughts from a guy who made it through high school and college, and now teaches and coaches kids daily:
I teach two 8th grade physical science classes. To be perfectly honest, you have to TRY to get below a B in my class the way the curriculum is set. I give "completion" grades for homework (I reteach all concepts the class is struggling with, homework is used for ME to see what I need to cover more in depth,) weekly in class projects and assignments that we do together, complete study guides for tests that I make AFTER I make the test and follows the test almost exactly, and I have my students keep a vocabulary notebook for the semester that requires them to spend 5 minutes in class to copy down 4-5 definitions. I don't even move on to the lesson until everyone has had time to complete vocab.... and the notebook is 10% of the grade for the class!
Here is why I gave the background. Out of my 2 classes, one is a class on a "honors" track and the other is not. No student has below a B in my "honors" track science class. In my non-honors track class, The grades run the entire scale from A-F.
Is my non-honors class stupid? No! The kids in that class are every bit as intelligent, and in some cases more so, then the honors class. The difference is work ethic and attitude. The percentage of missing homework assignments between the 2 classes is unbelievable. The amount of study time spent by the students in the 2 classes is also vastly different.
So, here's the point. Achievement in high school has very little to do with intelligent, and everything to do with work ethic and attitude. Focus on applying yourself and making yourself a better student and building a better life for yourself. Get a college degree and find a job that fulfills your life. D's should never be acceptable. Even if your parents seem to think it's okay, you should never accept it for yourself. You should NEVER strive to be average. Strive to be the best. That attitude will take you further in life.
JR