To choose the best answer to complete the sentence "Kathy_ because her cat_away," we need to consider the correct tense and subject-verb agreement.

1. **A. Cries - run**
- "Cries" is present tense, and "run" is also present tense but does not agree with "cat" (singular subject). The correct form should be "runs" if it were present tense.
- This option is incorrect because "run" does not match the singular subject "cat."

2. **B. Cried - runs**
- "Cried" is past tense, and "runs" is present tense.
- This option is incorrect because the tenses do not match. Both verbs should be in the same tense to maintain consistency.

3. **C. Cry - ran**
- "Cry" is present tense, and "ran" is past tense.
- This option is incorrect because the tenses do not match. Both verbs should be in the same tense to maintain consistency.

4. **D. Cried - ran**
- "Cried" is past tense, and "ran" is also past tense.
- This option is correct because both verbs are in the past tense, which maintains consistency in the sentence.

Therefore, the best answer is:

**D. Cried - ran**

Explanation: The sentence "Kathy cried because her cat ran away" uses the past tense for both verbs, which is appropriate for describing a completed action in the past.