are all diagonals also lines of symmetry? and can you explain why?

Aphrase is shown read the phrase and give me the answer

Carl is hanging pictures in his home. there is a space on a wall that has a width of 4 feet. carl has pictures with different widths. which picture width would fit in the space on the wall? a. 46 inches b. 60 inches c. 50 inches d. 54 inches

The length of a rectangle plus its width is 24 cm. the area is 143 square cm. what are the length and width of the rectangle?