Answer:
Which sentence features an introductory clause that explains why the main action happened? its 3, Worried about her sister, Kayla called Jayla's cell phone.
Which sentence features an introductory phrase that explains why the main action happened? its 4 Because she took her eyes off the road to answer the phone call, Jayla lost control of her car and crashed through the front of Kayla's house.
good luck:D