The statement that best describes Kennedy's domestic achievements during his time in office is the second one: Kennedy wasn’t able to get much done due to opposition from Republicans and conservative Democrats in Congress.
Kennedy had very progressive legislative programs and reforms in mind, but conservative members from his own party (most of them Southern senators) prevented him from implementing them. He proposed economic reforms, such as increasing the minimum wage and lower the taxes, as well as social reforms, such as providing medical assistance for the elderly and promoting racial integration in the schools, but unfortunately he lacked the support from Congress to fully carry them out - at least while living; after his death, a civil rights bill known as the Civil Right Act of 1964 was passed.