Each microfossil group has its own start date in the fossil record, set by when it first evolved, and its range runs from that start date up to today if it still has living members. The question wants the groups whose start date goes all the way back to the Cambrian.
- Foraminifera: shelled single-celled organisms that first turn up in Cambrian rocks and are still common in oceans today, so their range is Cambrian to Recent.
- Diatoms: silica-shelled algae that only appear from the Jurassic onward, so their range is Jurassic to Recent, missing the earlier part of the Palaeozoic entirely.
- Radiolaria: silica-skeleton protozoa with a fossil record that, like foraminifera, reaches back to the Cambrian and continues with living species today, so their range is also Cambrian to Recent.
- Dinoflagellates: their fossil cysts are reliably recorded only from the Triassic onward, so their range is Triassic to Recent, again starting well after the Cambrian.
Only foraminifera and radiolaria push all the way back to the Cambrian, diatoms and dinoflagellates both start much later in geological time.
Let's summarize:
- Foraminifera: Cambrian to Recent.
- Radiolaria: Cambrian to Recent.
- Diatoms: Jurassic to Recent.
- Dinoflagellates: Triassic to Recent.
So the microfossils ranging from Cambrian to Recent are Foraminifera and Radiolaria.