Please answer the following question: Read the article and select the best answer. Article: A study found most people use their smart phones for an hour and 52 minutes a day. Most of this time is taken up with texting, emails and surfing the web, but only around 20 minutes is spent making three calls. The survey of 2,000 people found that social media apps, calculators , calendars and cameras were also seen as particularly important functions. Navigation apps such as Google Maps were popular too - with one in six people admitting they would feel unable to travel around an unfamiliar city without _ . The study also found checking Facebook and taking pictures of others are carried out more frequently than making calls. Also on the list were the calendar to remember appointments and birthdays, mobile banking and the news are apps that make day-to-day life a little easier. Tom Barr said: 'The functions on a mobile phone have developed and improved drastically over the past 10 years. With so many ways to keep in touch nowadays, people are using the functions that are convenient for them. As we get less and less time to ourselves, we need more convenience in our lives and less difficulty. While calling can be more personal, it doesn't always save your time.' Scientists at Rice University wanted to see if the latest mobile technology would be used by the students to improve their learning. But a year later, the researchers concluded that it's not enough to give students the right technology, but said they need guidance about how to use it. Question: The writer mainly wants to tell us _ . Options: A: navigation apps such as Google Maps were popular B: checking Facebook is carried out more frequently than making calls C: the functions on a mobile phone have developed and improved drastically D: students need guidance about how to use mobile phones
A:
C