Step 1: Understand the relationship.
Since \( p \) is the probability that event \( E \) will occur, and \( s \) is the probability that event \( E \) will not occur, we know that:
\[
p + s = 1
\]
because either event \( E \) will occur or not occur.
Step 2: Compare the quantities.
Now, we are comparing \( p + s \) with \( ps \). Since \( p + s = 1 \), we need to check the value of \( ps \) for different values of \( p \) and \( s \).
For example, if \( p = 0.5 \) and \( s = 0.5 \), then:
\[
ps = 0.5 \times 0.5 = 0.25
\]
Here, \( p + s = 1 \) is greater than \( ps = 0.25 \).
Step 3: Conclusion.
Since \( p + s = 1 \) and \( ps \) will always be less than 1, the correct answer is that Quantity A is greater.
Final Answer:
\[
\boxed{\text{The correct answer is (1) Quantity A is greater.}}
\]