Choose the letter A, B, C, or D to indicate the sentence that best combines the following pair of sentences.

We developed a subway system. It was to improve the transportation in the city.

A. Functions of a public library

B. What a public library focuses on

C. What services a public library offers

D. How to obtain a public library card

A. that

B. what

C. which

D. when

A. The earthquake took many months to destroy the area and rebuild it.

B. People want to rebuild the town which was destroyed by the earthquake.

C. It took many months to rebuild the area destroyed by the earthquake.

D. The town was destroyed but not rebuilt after the earthquake.

A. You can wear a swimming cap in the pool if you want.

B. You should not wear a swimming cap in the pool.

C. Wearing a swimming cap in the pool is optional.

D. Swimming caps must be worn in the pool.

A. Members have to use all the facilities in the center.

B. Members should be allowed to use all the facilities.

C. Facilities must be used by only members.

D. The center should develop its facilities.

A. Visitors can try wearing protective clothing.

B. Under no circumstances should visitors take off their protective clothing.

C. Protective clothing must be paid for by visitors.

D. Visitors must on no condition put on protective clothing.