A. This is the reason for achieving high academic excellence.
B. All these professors are highly qualified.
C. This university has completed 100 years.
D. Initially, the university had only six departments.
E. Now, it has 100 professors working in 30 departments.

Let us understand the important nouns and phrases in each sentence and try to arrange them sequentially. 
reason for success-highly qualified professors-100 year university-initial departments-current status

We are looking for a sequence of sentences that introduces the university, takes you on a journey from the initial status to the current status and how the statute of its professionals leads to success. 
C. This university has completed 100 years.
D. Initially, the university had only six departments.
E. Now, it has 100 professors working in 30 departments.
B. All these professors are highly qualified.
A. This is the reason for achieving high academic excellence.

Hence, the correct order of sentences is CDEBA.