Explanation:

In the sentence 'गुरु ही शिष्य को ज्ञान देता है' (The guru gives knowledge to the disciple), the phrase 'शिष्य को' (Shishya ko) indicates the recipient of the action of giving. When 'को' (ko) is used to denote the receiver to whom something is given or for whom something is done, it signifies the 'संप्रदान कारक' (Sampradan Karak), which is equivalent to the Dative case. Option (1) 'कर्म कारक' (Karma Karak) uses 'को' for the direct object, but here 'ज्ञान' (knowledge) is the direct object. Option (3) 'करण कारक' (Karan Karak) indicates the instrument or means, and (4) 'संबंध कारक' (Sambandh Karak) shows possession or relationship, neither of which applies here.