Final answer:
The most appropriate instructional focus for the ESL teacher is basic sentence structure.
Step-by-step explanation:
The most appropriate instructional focus for the ESL teacher to use with the ELLs based on the writing samples is Basic sentence structure. The writing samples exhibit errors in sentence structure, such as long-winded sentences, incorrect word order, and missing articles. By focusing on basic sentence structure, the teacher can help the students improve their ability to form grammatically correct sentences in English.