56.—For the purposes of subsection (1) of section 34 and subsection (1) of section 46, the fact that any person—

(a) had an opportunity of avoiding the consequences of the act of any other person but negligently or carelessly failed to do so, or

(b) might have avoided those consequences by the exercise of care, or

(c) might have avoided those consequences but for previous negligence or want of care on his part,

shall not, by itself, be a ground for holding that the damage was not caused by the act of such other person.