Your title depends on what your text and reasons are specifically about and what the information you are given is, however I would choose whichever one fits your information the best. However, they all are talking about bicycles. I would most likely choose the health benefits of bicycling.
Answer: punctuation and spelling
Explanation: Those are the two most prominent things grammatically in writing
B. Nothing about the Navajo's artistry in jewelry and textiles helped the Allies during WWII, although using their language as a code definitely did.
<u>Answer:</u>
My dear Father,
I am fine here and I hope you will receive this letter in the best of health. I received your letter ten days ago but I was busy in my midterm exams so couldn’t write to you earlier. You seemed quite concerned about my studies as my previous result was below 80%. The result of the midterm exams has been announced and you will be delighted to know that I have got 88% marks in it. I owe this success to god's favour, your prayers and blessings and the proper guidance of my worthy teachers. For the final exams, I shall have to work hard even more. I find difficulty in mathematics and I am planning to get private coaching in it. I didn’t prepare myself well enough in Pakistan. studies and I am concentrating on it as well. Moreover, I’m trying to improve my writing speed because at times I cannot mange to complete the paper. I want to assure you that I have recognised my failings and now trying my utmost to improve them. I have reduced my sleeping hours.I have learned that one cannot climb the ladder of success with one’s hands in pockets.
I know your wishes and support are my strength and I will prove myself in studies. Pay my compliments to all at home.
Your loving son/daughter,
________
warrant/support is were it should be