Combine the sentences, using “adjective + for somebody + to-injinitive”.
Use an electronic calendar to write down the things you need to do, including appointments and deadlines. It is very simple.
=> _________ an electronic calendar to write down the things you need to do, including appointments and deadlines.
A. It's very simple use
B. It's very simple using
C. It's use very simple
D. It's very simple to use