Assuming I have interpreted your question correctly, the main options are Scala or Python, while there are minor differences, I would suggest you choose whichever language you, your team, or your company are more comfortable with.
Hope that helps.
Apache Spark is written in Scala. Scala gets first level support and Spark runs on the JVM, Python has some performance issues and is not usually recommended in Production for Spark.
Scala is the natural language for Spark as the APIs are based on Scala Idioms.