Pineapple
- Pineapple is not the correct answer. Although it has a rough exterior, its flesh is yellow and not white.

Dragon fruit
- Dragon fruit is the correct answer. It is known for its rough, spiky exterior and sweet white flesh inside.
- The exterior of the dragon fruit is covered in bright pink or yellowish-green spiky scales. These scales give it a unique appearance and make it easily recognizable.
- When you cut open a dragon fruit, you will find that its flesh is white with black seeds speckled throughout. The flesh has a sweet and mild flavor, often compared to a mix of kiwi and pear.
- Dragon fruit is also known by other names such as pitaya or strawberry pear. It is native to Central and South America but is now cultivated in many other parts of the world, including Southeast Asia.
- Dragon fruit is not only delicious but also packed with nutrients. It is a good source of vitamin C, antioxidants, and several minerals. It is also low in calories and high in fiber, making it a healthy choice for a snack or addition to various dishes.

Kiwi
- Kiwi is not the correct answer. While it has a rough exterior, its flesh is green and not white.

Mango
- Mango is not the correct answer. It has a smooth, sometimes slightly rough, skin, but its flesh is orange or yellow, not white.

In conclusion, the fruit known for its rough, spiky exterior and sweet white flesh inside is the dragon fruit. Its unique appearance and delicious taste make it a popular choice among fruit enthusiasts.