Step 1: Understanding the events in meiosis
Synapsis occurs in the zygotene phase and leads to bivalent formation (I).
Crossing over occurs in the pachytene phase and results in the recombination of genes (II).
Step 2: Evaluating the options
Option (1): Incorrect, as III and IV are incorrect.
Option (2): Incorrect, as IV does not align with the correct combination.
Option (3): Correct, as both I and II are correct.
Option (4): Incorrect, as III and IV are not correct combinations.
Final Answer: \[
I\text{ and }II
\]