If  p > 0 and  q < 0, then:

Given:
​$$p > 0, \quad q < 0 \\$$​​
Concept used:
Subtracting a negative number is equivalent to adding a positive number:
​$$p - q = p - (\text{negative}) = p + (\text{positive}) > p \\$$​​
​$$\Rightarrow p - q > p \\$$​​
Correct answer is (c).