In this passage from Morte d’Arthur by Sir Thomas Malory, the key word to understand the whole idea of the happenings is: adder, it means snake.
And if you still have doubts about the general idea of the passage and think that the first three options: “King Arthur attempts to slay, or kill, Sir Mordred”. “Sir Mordred fatally wounds King Arthur”.” King Arthur and Sir Mordred are expressing their distrust of each other.” Can be correct, read this sentence:
“and so rode to his party, and Sir Mordred in likewise.”
None of the first three options can be posible if the two of the knights go together to a party afterwards.
The right answer is:
A knight kills a snake with his sword.
