a) Natividad's holographic will, which had only one (1) substantial provision, as first written, named Rosa as her sole heir. However, when Gregorio presented it for probate, it already contained an alteration, naming Gregorio, instead of Rosa, as sole heir, but without authentication by Natividad's signature. Rosa opposes the probate alleging such lack of proper authentication. She claims that the unaltered form of the will should be given effect. Whose claim should be granted? Explain. (5%) b) John Sagun and Maria Carla Camua, British citizens at birth, acquired Philippine citizenship by naturalization after their marriage. During their marriage, the couple acquired substantial landholdings in London and in Makati. Maria begot three (3) children, Jorge, Luisito, and Joshur. In one of their trips to London, the couple executed a joint will appointing each other as their heirs and providing that upon the death of the survivor between them, the entire estate would go to Jorge and Luisito only but the two (2) could not dispose of nor divide the London estate as long as they live. John and Maria died tragically in the London subway terrorist attack in 2005. Jorge and Luisito filed a petition for probate of their parents' will before a Makati Regional Trial Court. Joshur vehemently objected because he was preterited. 1) Should the will be admitted to probate? Explain. (2%) 2) Are the testamentary dispositions valid? Explain. (2%) 3) Is the testamentary prohibition against the division of the London estate valid? Explain. (1%)