1. a common noun does not usually begin with a capital letter
and a proper noun does . A proper noun is not more polite than a common noun, so the answer is D. A proper noun is MORE specific than a common noun
2. B. it would be brought. A is not correct because it is saying u brought u diary everyday except for today. C is not correct because bringing is present and Bring is past tense but it is saying that i'll bring my diary TOMORROW which makes it present
In the first question, the answer is - D. A - cannot be the correct answer as common nouns (such as - chair, computer, desk) don't have to be written in capital letters. And regarding B, proper nouns (such as John, Thames. America) always have to begin with a capital letter. C - is simply incorrect, using proper nouns, that is, names, isn't more polite than saying, for example, a wall.
Regarding the second question, the answer is - B. It is the only sentence in which the past simple tense of the verb "to bring" is used. The first example uses the present perfect tense (which isn't a past tense), C - present continuous, and D - future simple.