The correct option is D oneself, itself
Pronouns replace nouns that have been mentioned before or in the previous statement, to avoid repetition. There are many types of pronouns, reflexive pronouns being one of them. They're used when the subject of a sentence (I, you, she) performs an action that falls back on that subject (myself, yourself, herself), reflexive pronouns are the object of an action, where the subject and object are the same person. Emphatic pronouns are the same, but they're used for laying emphasis on that pronoun, 'I myself went there'. Here we're given two statements, they speak about a general truth. In the first statement, the subject is "one", that refers to any person, in general. It performs the action "protects" towards its own self, 'oneself', as the statement speaks about protecting the self. 'Itself' is used for things or animals, and the pronoun "one" determines which reflexive pronoun is to be used, hence 'itself' is incorrect for the first part. Also, in the second statement, the subject is "risk", which should be followed by an emphatic pronoun that lays emphasis on that risk. It's a thing, hence 'itself' is the correct emphatic pronoun, as opposed to 'oneself', used for people. Hence option A is incorrect. 'Myself' cannot be used as the speaker is not talking about himself, but a person in general 'one'. Also, in the second statement the subject is "risk", which is a singular thing, whereas 'themselves' refers to a plural noun, that too for people, hence it's incorrect. So, options B and C are both incorrect. The remaining option is D, which has the correct answers, so we choose this option.