which of these is a proper way to change the following sentence to passive voice?
Geologists determined that the shine coming from the rocks had a greater frequency than they thought
a. the shine coming from the rocks was determined to have a grater frequency than geologists thought
b. Geologists determined shine coming from the rocks with a greater frequency than they thought
c. Geologists determined that the shine from the rocks had a greater frequency than they thought
d. the shine coming from the rocks had a greater frequency than geologists thought