1. **State the problem:** We need to find Clara's number which satisfies three conditions: - It is prime. - It is a factor of 68. - It is odd. 2. **Find the factors of 68:** The factors of 68 are numbers that divide 68 without leaving a remainder. $$68 = 1, 2, 4, 17, 34, 68$$ 3. **Identify which factors are prime:** Among these factors, the prime numbers are 2 and 17. 4. **Check which prime factors are odd:** 2 is even, 17 is odd. 5. **Conclusion:** The only number that meets all the conditions is 17. **Final answer:** Clara's number is $17$.