The decline and fall of the Roman Empire remains a topic of vigorous debate to this day; historians have attributed it to a variety of causes, including military insurrection, ethnic conflict, and widespread immorality.
1. have attributed it to a variety of causes, including military
insurrection, ethnic conflict, and
2. attribute it variously to causes that include military
insurrection,ethnic conflict, or
3. have variously attributed them to causes which include military
insurrection, ethnic conflict, and
4. attribute them to various causes, including military insurrection,
ethnic conflict, as well as
5. variously attribute them to causes including military
insurrection, ethnic conflict, and
Confusion - The decline and fall of the Roman empire - How can this phrase be singular.The usage of and between the decline and Fall suggests that its a plural construction.
Please clarify!
Thanks in Advance.