The correct option is C Straight posterior part
Ascaris are the unisexual and shows sexual dimorphism. The male worm measure 12-23 cms in length and 3-4 mm in diameter. The tail (posterior end) is curved ventrally in the form of a hook, with a conical tip. Whereas the female worm is longer and stouter than males measuring 25-49cms in length and 5mm in diameter. The tail ( posterior end ) is straight and blunt. Thus, the correct answer is option A.