Well, I would say a math teacher would say D is the correct answer. Obviously, the missing piece of the equation is any mention of units.
Without any reference to units, 3 can't equal 2. There's no point in having a linear numerical system expressing unique values and then have two distinct numbers equal to one another. As soon as you throw units in, however, the equation makes perfect sense.
I gave one hint- Clif Block Shots. That's the three. Normally, when I'm doing either a bike ride or a brick, I eat one bag every thirty minutes. However, I bought the entire supply they have at Zane's Bicycles and after calculating what I though Margit would need for her Saturday ride, I decided that I could only take a maximum of 4 bags, and then run with just Gatorade. The ride was three hours long.
When I don't have enough blocks, I go with a 40 minute gap and eat until I run out.
So the answer is 4 = 2 2/3. Not a bad plan, actually, as that allowed me to 'carry' the calories from the last bag 20 minutes into my run.