Some one please help me in 14 and 15

Choose the correct answer. the phrase "por cierto" means: by certain for sure over there for now does anyone know the answer to this question?

El monte aconcagua, en argentina, mode 6,960 metros de altura .la península valdés ,en argentina ,está a 40 metros bajo el nivel del mar.¿cual es la diferencia en metros, de elevación entre estos dos lugares?

Which one of the following is a trick used in spanish to identify the right hand? touch the tips of your index fingers with the tips of your thumbs. the hand that forms a lowercase b is your mano derecha. touch the tips of your index fingers with the tips of your thumbs. the hand that forms a lowercase d is your mano izquierda. touch the tips of your index fingers with the tips of your thumbs. the hand that forms a lowercase d is your mano derecha.