The second choice is the correct one.
You can spot it just from the units. An equation can't be true unless it has the same units on both sides.
Wavelength has units of (meters).
Frequency has units of (per second).
When you multiply them, you get (meters per second), the unit of speed, and the 'c' on the other side is speed.
None of the other choices has units of speed on the right side.
