Define parallel lines.
A) If two lines are such that they meet one another on producing from both the sides then they are said to be parallel to each other.
B) If two lines are such that they meet one another on producing from one of the sides then they are said to be parallel to each other.
C) If two lines are such that they never meet one another on producing from both the sides then they are said to be parallel to each other.
D) None of these

Hint: Parallel line is the most frequently used line in geometry. We are familiar that these lines never meet each other. So we'll just catch these words from the options.

Complete answer:
Parallel lines can be defined as the lines in the same or different plane but that never meet each other.
Thus we will check the options one by one.
In option (A), the first statement is “ they meet each other”. This directly cancels the option ; no need to read further.
In option (B), though it is produced from one side or both sides but they should not meet. But the option says they meet. So this is not our answer.
And option (C) is “they never meet” and this is the correct and most appropriate answer because the lines are produced on both sides also.

These are the parallel lines.
Thus, option (C) is the correct definition of parallel lines.

Note:
Note that we generally read half the option and tick the answer. Read the full option statement because the initial words might be positive or answer carrier but the remaining or half of the portion cannot be. So do read the full option.
Also note that angle between the parallel lines is always zero this also means they never meet each other.