Combine the sentences, using “adjective + for somebody + to-injinitive”.
To use a time log is useful for eliminating wasted time. (way)
A. It is one useful way to eliminate wasted time is to use a time log.
B. One useful way eliminating wasted time is to use a time log
C. One useful way to eliminate wasted time is to use a time log.
D. One useful way to eliminate wasted time is using a time log.