((a)) In the case of a child entitled to dependency and indemnity compensation who has attained the age of eighteen and who, while under such age, became permanently incapable of self-support, the dependency and indemnity compensation paid monthly to such child shall be increased by $286.
((b)) If dependency and indemnity compensation is payable monthly to a person as a surviving spouse and there is a child (of such person’s deceased spouse) who has attained the age of eighteen and who, while under such age, became permanently incapable of self-support, dependency and indemnity compensation shall be paid monthly to each such child, concurrently with the payment of dependency and indemnity compensation to the surviving spouse, in the amount of $488.
((c)) If dependency and indemnity compensation is payable monthly to a person as a surviving spouse and there is a child (of such person’s deceased spouse), who has attained the age of eighteen and who, while under the age of twenty-three, is pursuing a course of instruction at an educational institution approved under , dependency and indemnity compensation shall be paid monthly to each such child, concurrently with the payment of dependency and indemnity compensation to the surviving spouse, in the amount of $243.