Solution

The correct answer is option 3.

Key Points

• "alignment rules" that "require the address of every primitive data element to be an even multiple of the element’s size". It's not very interesting that we're talking about alignment rules; we knew that already.
• "require the address" of "every primitive data element" to be "an even multiple of the element’s size". Now we're getting somewhere. We have a requirement and a scope:
• Requirement: The address is an even multiple of the element's size.
• Scope: Every primitive data element.
• So, every time we position an element, we must impose the requirement. It may also mean "even" as in "integral" rather than "multiple of two" 

That would make the array:

In that case, you have 24 bytes per element for a total of 240 bytes. Again, you need padding to ensure that r is aligned correctly.

∴ Hence the correct answer is 240 bytes.