Final answer:
The phrase 'A. plunge into' provides context clues to the meaning of 'venture,' suggesting an undertaking involving risk or daring action.
Step-by-step explanation:
The phrase that helps the reader determine the meaning of 'venture' as used in paragraph 3 is A. plunge into. This phrase suggests an action, implying that 'venture' in this context likely refers to some type of undertaking or action involving risk or daring. For instance, if the sentence read, 'She decided to venture into the unknown,' and is followed by 'taking a bold step' or 'plunge into,' it implies that 'venture' means to undertake something that is possibly risky.