When upgrading a tower, do the bonus damage points add up?

For example, for a level-5 javelin tower, the basic damage is 26 - 35. The tower can be further upgraded by spending mana on “Sharper Javelin” upgrades: the first upgrade gives +20 extra damage, the second one gives +30 damage, and the third one gives +50 damage.

If I upgrade the tower three times, what damage does the tower deal?

Is it A or B (below)?

A). Minimum is 26 + 20 + 30 + 50 = 126

    Maximum is 35 + 20 + 30 + 50 = 135

B). Minimum is 26 + 50 = 76

    Maximum is 35 + 50 = 85