Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 36 to 42.

Once your child is born, they start learning motor skills, language skills, cognitive skills, and emotional skills. Regarding motor skills, it is largely the family’s responsibility for teaching these skills. Even if your child is in daycare, the work that parents put in at home to teach these skills is much more effective than in the few hours your child is under someone else's care. Your child will learn how to sit up, walk, run, climb, hold a spoon and so on. These seem quite natural to us as adults, but they are skills that have to be fine-tuned at a very young age, and they also reinforce your child’s independence which is essential for their development. Language skills are another essential component of the role of family in child development. If you do not speak to your child and teach them your language, they will never learn. One infamous example of this occurring is with Genie, a child who was locked in a dark room with extremely little human contact until she was rescued at age 13. She was never able to develop language fluency because it was never taught to her. So, teaching your children language skills from a young age is also essential to child development. Another skill that is very important for child development is emotion. Emotional skills are important throughout your child's entire life as they teach them when to have sympathy and compassion for others as well as teach them how to deal with the highs and lows that come with life. If your child does not have proper emotional skills, they will not be able to deal with bad outcomes. If they lack emotional skills, it could lead to destructive choices when they are older. To help develop your child's emotional skills, teaching them to smile and wave when they are babies is a good place to start. When they get a bit older, teaching them to share is very important. In a family, because there are multiple people, the family can be very helpful in developing a child's skills with the multiple perspectives. To bring this more to foundational building blocks, while your child is very young, something very helpful for family members to do is to teach children basic emotions. When a child is feeling a certain way, naming emotions and describing them are important ways for your child to understand how they are feeling. Once this foundation is set, children can learn how to respond to their feelings and move forward. (Adapted from https://www.all4kids.org/)

We should think carefully because the problem is a _______ nut to crack. A. tight B. hard C. firm D. fit