Answer:
1price 1 price price 1
Step-by-step explanation:
In the c programming, the rule for valid variable name.
1. Variable name cannot start with numeric value like 1,2,3..
2. Space and special character other than underscore '_' are not allowed.
3. After the first letter, numeric values can be used.
Let discuss the options:
Option A: 1price
it start with number which is not allowed.
Option B: 1 price
it start with number and also contain the space which is not allowed.
Option C: price 1
it contain the space which is not allowed.
Option D: price1
it is the valid variable name, start with letter and their is no space.
Therefore, option A, B and C are correct option.