The sentences "The dog chased the cat" and "The cat chased the dog" mean different things even though they contain the same words. This is because of .

Syntax.

Explanation:

What Syntax studies is the principles and processes of sentences in a particular language, including the word order. In this case, the sentences "The dog chased the cat" and "The cat chased the dog" mean different things because of the word order: The dog chased the cat means that the dog was running behind the cat, after him. If the cat chased the dog, the opposite. In this simple example we notice the importance of syntax and the word order in a sentence. It's not the same if we say "The man was helped by the medic" rather than "The medic was helped by the man" even if it shares the exact same words.

The question says,'validity that involves how well a study is designed and administered is validity. The correct option is A. internal validity refers to how well a research project was conducted. The objective of most projects is to show that one variable causes a change in another variable, therefore it is part of internal validity to ensure that more than one independent variable do not act at the same time.