Which of the following are TRUE for Treponema pallidum?

1. It is the causative agent of syphilis
2. It is a spirochete
3. It is a non-motile bacterium
4. It is generally susceptible to penicillin

Choose the correct combination.

1. P, Q and R only
2. P, Q and S only
3. P, R and S only
4. Q, Rand S only