Answer:
The answer is double helix.
Explanation:
In its natural state, each DNA molecule is actually composed of two single strands held together along their length with hydrogen bonds between the bases. Watson and Crick proposed that the DNA is made up of two strands that are twisted around each other to form a right-handed helix, called a double helix.
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Provided that there's no diagram, most molecules have particular areas on the molecules, called the "active area" that act as a lock to a particular substrate's molecular structure, providing the key.
An enzyme's active area is only able to be "unlocked" by a certain substrate's "key".
Answer:
1-C............. ...............