Option 1 states that Rajmahal highlands consist of lava flow deposits. This means that the highlands in Rajmahal are made up of solidified lava that once flowed. This statement is correct.
Option 2 states that Bundelkhand gneiss belong to the oldest Achaean rocks of India. The term "gneiss" refers to a type of metamorphic rock that forms from the alteration of pre-existing rocks under high temperature and pressure conditions. The term "Achaean" refers to a geological period that occurred around 3.8 to 2.5 billion years ago. Therefore, this statement suggests that the Bundelkhand gneiss is one of the oldest rocks in India, dating back to the Achaean period. This statement is also correct.
Since both statements 1 and 2 are correct, the correct answer is option 3, which says that both statements are true.
In conclusion, both Rajmahal highlands consisting of lava flow deposits and Bundelkhand gneiss belonging to the oldest Achaean rocks of India are correct statements.