macro to shade every other group of data

Hello all,
Ever have one of those really big reports that, if the different lines weren't shaded, would be virtually impossible to read? I am looking to have a macro which will look for data in column C and shade entire rows of every other block of data.

Is this possible? I have attached a spreadsheet as an example of what I am looking to do.

I saw a lot of threads on macros for every other row, but not every other block of different data.

Thanks in advance!

FYI, it can also be done with conditional formatting. See attached.