Which represent a) Matched Pairs, and which represent b) Independent samples?

Which represent a) Matched Pairs, and which represent b) Independent samples?

1-Comparing the number of speeding tickets received by men to the number received by women

2-Comparing pain levels of a group receiving a placebo to a group receiving a medicine

3-Comparing pre-test scores before training to post-test scores

4-Comparing pain levels before and after treatment with magnetic therapy