35 year old female patient Radha having children aged 5 and 6 years has history of amenorrhea and galactorrhea. Blood examination reveals increased prolactin. CT of head is likely to reveal:
Patient is presenting with amenorrhea; galactorrhea with raised prolactin levels. So lets rule out some of the options:
Sheehan's Syndrome 
• In Sheehan's syndrome there is failure of lactation (due to ischemic necrosis of anterior pituitary) and not galactorrhea (so, option "c" ruled out).
Pinealoma: 
• If you go through the list of causes of hyperprolactinemia given in Harrison 17th/ed p 2205; Table 333-8 - Pinealoma is not one of the causes. (as there is no reason for a pineal gland tumor to raise prolactin levels), ruling out option "d".
That leaves us with 2 options:
Pituitary adenoma and craniopharyngiorma: Both are pituitary tumors which can present with amenorrhea galactorrhea, and raised prolactin levels.
Now comes the age factor - Craniopharyngiomas present usually before 20 years (Harrison 1762/ed p 2201) of age and so by exclusion: Option "a" i.e. Pituitary adenoma seems more likely as the cause.
"In patients with both galactorrhea and amenorrhea approximately two-thirds will have hyperprolactinemia, in that group approximately one third will have a pituitary adenoma."
So, pituitary adenoma is more common than craniopharyngioma and this confirms our answer.
Pituitary adenoma
Craniopharyngioma
Sheehan's syndrome
Pinealoma