Many insects have a tough outer shell called an exoskeleton cellulose an endoskeleton chitin

An exoskeleton.

Explanation:

Tough outer shell of many insects is known as exoskeleton that represents an external skeleton. The exoskeleton provides protection and support to the insects body as they lack an internal skeletal system as higher organisms. In insects, it is made up of chitin.

Exoskeleton also plays role in sensing, feeding, excretion, and protection against desiccation in land insects.

Thus, the correct word to be filled in the blank is 'exoskeleton.'

the correct answer is: d. the saltine and pretzel are made of flour, yeast, and baking soda, and salt. the pecan contains no flour but it does contain fats. the pecan is a nut that can be consumed as a healthy snack. first of all, pecans are a source of fat (monounsaturated fat), but they provide less fat than some other nuts. pecans are a rich source of dietary fiber, manganese magnesium, phosphorus, thiamin, vitamin e…

answer; i believe the correct answer is (a)0