Egypt, rocks and contruction

[Ashish1354]

Original sentence : Ancient Egypt had an abundance of rocks quarried close to the banks of the Nile.

These rocks had to be brought from quarries to the building sites.

Following are the corrected versions

(a) Ancient Egypt had an abundance of rocks quarried close to the banks of the
Nile, so these rocks had to be brought from quarries to the building sites.

(c) Ancient Egypt had an abundance of rocks quarried close to the banks of the
Nile, but these rocks had to be brought from quarries to the building sites.

Which one out of the two options is more desireable and why?

[Mister Micawber]

.
Neither, really-- both independent clauses place too much importance on what should be obvious: that the rocks had to be transported. I suggest:

Ancient Egypt had an abundance of rocks quarried close to the banks of the Nile, which had to be brought to the building sites.
.
_________________
Native English teacher at Mister Micawber's