You should . . . . . . . . swimming. A. start up B. get off C. take up D. take off

start up
get off
take up
take off

The correct answer is C. take up.

The other options are incorrect because:

  • A. start up means to begin something, but swimming is already something that you do.
  • B. get off means to leave something, but you are not leaving swimming.
  • D. take off means to remove something, but you are not removing swimming.

To take up something means to start doing it regularly. In this case, the speaker is suggesting that you should start swimming regularly.