The underlined verb is 'is observed.' The form of that verb is B. passive.
Active form would be 'People observe the National Yo-Yo Day...' Imperative form is giving commands, so it would be something like - Please go and observe that! Subjunctive form would be - If I were you,I would observe...
Number 4. It Needs To Relate To Your Claim
To control society, set laws, and to provide services like the building of roads through tax money
The liquid in the bottle <u>smells</u> like some kind of acid.