What does the speaker say is essential for teachers in the United States?

Listen to the conversation.
Then read the four choices marked A, B, C, and D, and decide which is the best answer according to what you hear.
M: Hello and welcome to our fifth career choices seminar! Today we have Wendy Smith here to give us some information on the teaching career in the United States.
W: Hello.
M: First of all， can you tell us what personal qualities teachers need to have?
W: In addition to being knowledgeable in their subject， teachers must have the ability to communicate， inspire trust and confidence， motivate students， as well as to understand their educational and emotional needs. It’s essential for teachers to be able to recognize and respond to individual differences in students， and employ different teaching methods. They should be organized， dependable， patient and creative. They must also be able to work cooperatively and communicate effectively with other teaching staff， support staff， parents， and other members of the community.
M: How many teachers are employed in the United States?
W: I have some data here from the year 2017， and teachers and related staff held about 10.1 million jobs that year. Of those， about 4.6 million were school teachers， and 5. 5 million were other teaching staff. Employment is distributed geographically， in much the same way as the population.
M: What kind of training and qualifications do teachers need to work in the United States?
W: All 50 states and the District of Columbia require public school teachers to be licensed. Licensing is not required for teachers in private schools. Teachers may be licensed to teach the early childhood grades， nursery school through grade 3， the elementary grades 1 through 8， the middle grades 5 through 8， a secondary education subject area for grades 7 through 12， or a special subject， such as reading or music for grades K through 12.
M: What are the requirements for a license?
W: Requirements for regular licenses vary by state. However， all states require a bachelor’s degree and completion of an approved teacher training program as well as supervised practice teaching.
M: Finally， what challenges might teachers face in their careers?
W: Seeing students develop new skills and gain an appreciation of knowledge and learning can be very rewarding， however， this can also be a big challenge.