<prompt> Senescent RBCs are mainly attacked in-Vivax malariaOvale malariaFalciparum malariaQuartan malaria  <response>: P. malariae which attacks mainly senescent old RBCs: Agent of Quartan malariaP. ovale and P. vivax: attack younger RBCs and reticulocytes: Agent of benign tertian malariaP. falciparum: attacks RBC of all ages: Agent of malignant tertian malaria. 