(1) In this Chapter and subject to the following provisions of this section and to sections 128, 130 and 134(3) "relevant business property" means, in relation to a gift or inheritance, any one or more of the following, that is to say:

(a) property consisting of a business or interest in a business;

(b) unquoted shares in or securities of a company whether incorporated in the State or otherwise to which paragraph (c) does not relate, and which on the valuation date (either by themselves alone or together with other shares or securities in that company in the absolute beneficial ownership of the donee or successor on that date) give control of powers of voting on all questions affecting the company as a whole which if exercised would yield more than 25 per cent. of the votes capable of being exercised thereon;

(c) unquoted shares in or securities of a company whether incorporated in the State or otherwise which is, on the valuation date (after the taking of the gift or inheritance), a company controlled by the donee or successor within the meaning of section 16 of the Principal Act;