To solve this problem, we need to identify the hormones secreted by the placenta that help maintain pregnancy. Let's analyze each option:$\newline \bullet$hCG (human chorionic gonadotropin):$\newline$ - hCG is produced by the placenta shortly after implantation. It supports the corpus luteum, which in turn produces progesterone to maintain the uterine lining.$\newline \bullet$hPL (human placental lactogen):$\newline$ - hPL is produced by the placenta and helps in the development of the mammary glands and regulates maternal glucose, protein, and fat levels.$\newline \bullet$Progestogens:$\newline$ - These include progesterone, which is crucial for maintaining the uterine lining and preventing contractions during pregnancy.$\newline \bullet$Estrogens:$\newline$ - Estrogens are produced by the placenta and help in the growth of the uterus and the development of the fetal organs.$\newline$Now, let's evaluate the options:$\newline \bullet$Option 1: hCG, hPL, progestogens, estrogens - This option includes all the hormones mentioned above that are secreted by the placenta to maintain pregnancy.$\newline \bullet$Option 2: hCG, hPL, estrogens, relaxin, oxytocin - Relaxin and oxytocin are not primarily secreted by the placenta for maintaining pregnancy. Relaxin is involved in relaxing the pelvic ligaments, and oxytocin is involved in labor.$\newline \bullet$Option 3: hCG, hPL, progestogens, prolactin - Prolactin is primarily produced by the pituitary gland, not the placenta.$\newline \bullet$Option 4: hCG, progestogens, estrogens, glucocorticoids - Glucocorticoids are not primarily secreted by the placenta for maintaining pregnancy.$\newline$Therefore, the correct option is Option 1: hCG, hPL, progestogens, estrogens.