Is "Ram ne kitaab padha" correct?

Why

Arjun correctly remembered that past-tense verbs agree with the subject's gender ('सीता गई'), and reasonably tried applying that rule here too — but it isn't the whole picture. When a sentence has 'ने' (meaning the verb has its own object, like 'किताब'), the rule changes: the verb now agrees with the OBJECT's gender and number, not the subject's. 'किताब' is feminine, so the verb must be 'पढ़ी' (feminine form), even though the subject 'राम' is masculine — 'पढ़ा' is wrong because it tries to match Ram, but in 'ने' sentences the match is with the object. Test it: if Ram had read a 'पत्र' (letter, masculine) instead, it would be 'राम ने पत्र पढ़ा' (masculine, matching 'पत्र') — the same subject, yet the verb's form changes with the object. His sister is right: in 'ने' sentences the verb agrees with the object (किताब), not the subject — so 'राम ने किताब पढ़ी' is correct.