The correct statement(s) for orthoboric acid is/are:
It behaves as a weak acid in water due to self ionization.
It is a weak electrolyte in water.
Acidity of its aqueous solution increases upon addition of ethylene glycol.
It has a three dimensional structure due to hydrogen bonding.

(A) It does not undergo self ionisation in water but accepts an electron pair from water, so it behaves as weak monobasic acid. Hence, (A) is incorrect.
H₃BO₃ + H⁻OH ⇌ B(OH)₄⁻ + H⁺ (i)
(B) When treated with 1, 2-dihydroxy or polyhydroxy compounds, they form chelate (ring complex) which effectively removes [B(OH)₄⁻] species from solution and thereby produce a maximum number of H₃O⁺ or H⁺ ions, i.e. results in increased acidity
(C) Boric acid crystallises in a layer structure in which planar triangular BO₃³⁻ ions are bonded together through hydrogen bonds
(D) H₃BO₃ is a weak electrolyte in water as in water the pKa value of H₃BO₃ is 9.25.