The correct answer is: B. 78 ft. by 27 ft.
A lawn tennis court is a rectangular area enclosed by white lines. The court is 78 feet (23.77 m) long and 27 feet (8.23 m) wide for singles matches, and 108 feet (33.52 m) long and 36 feet (11 m) wide for doubles matches. The net is 3 feet (0.91 m) high at the center and 3 feet 6 inches (1.07 m) high at the posts.
The court is divided into two halves by a net. The service line is 21 feet (6.4 m) from the net in singles and 27 feet (8.23 m) in doubles. The baseline is 78 feet (23.77 m) from the net. The service box is a 21-foot-by-13-foot (6.4-by-4-meter) rectangle that is located on the side of the court where the server is standing. The service box is divided into two halves by a service line that is 18 feet (5.5 meters) from the net.
The court is also divided into two halves by a center service line. The center service line is located 27 feet (8.23 m) from the net and runs parallel to the baseline. The center service line divides the service box into two halves, the right service box and the left service box.
The court is further divided into two halves by the doubles alleys. The doubles alleys are two 6-foot-wide (1.83-meter) strips that run parallel to the baseline and are located 3 feet (0.91 m) on either side of the center service line. The doubles alleys are used in doubles matches only.
The court is also divided into two halves by the singles sidelines. The singles sidelines are two 2-foot-wide (0.61-meter) strips that run parallel to the baseline and are located 21 feet (6.4 m) on either side of the center service line. The singles sidelines are used in both singles and doubles matches.